[GlobalISel] Add Saturated Truncate Instructions #147526

jyli0116 · 2025-07-08T13:51:25Z

Introduces saturated truncate instructions to Global ISel: G_TRUNC_SSAT_S, G_TRUNC_SSAT_U, G_TRUNC_USAT_U. These were previously introduced to SDAG to reduce redundant code.

The patch only initially introduces the instruction, a later patch will follow to add combines and legalization for each instruction.

llvmbot · 2025-07-08T13:51:56Z

@llvm/pr-subscribers-llvm-support
@llvm/pr-subscribers-mc

@llvm/pr-subscribers-backend-aarch64

Author: None (jyli0116)

Changes

Introduces saturated truncate instructions to Global ISel: G_TRUNC_SSAT_S, G_TRUNC_SSAT_U, G_TRUNC_USAT_U. These were previously introduced to SDAG to reduce redundant code.

The patch only initially introduces the instruction, a later patch will follow to add combines and legalization for each instruction.

Patch is 23.10 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/147526.diff

10 Files Affected:

(modified) llvm/docs/GlobalISel/GenericOpcode.rst (+27)
(modified) llvm/include/llvm/CodeGen/GlobalISel/MachineIRBuilder.h (+42)
(modified) llvm/include/llvm/Support/TargetOpcodes.def (+9)
(modified) llvm/include/llvm/Target/GenericOpcodes.td (+21)
(modified) llvm/lib/CodeGen/MachineVerifier.cpp (+6)
(modified) llvm/test/CodeGen/AArch64/GlobalISel/legalizer-info-validation.mir (+9)
(modified) llvm/test/CodeGen/RISCV/GlobalISel/legalizer-info-validation.mir (+9)
(modified) llvm/test/MC/ELF/mc-dump.s (+1-1)
(modified) llvm/test/TableGen/GlobalISelCombinerEmitter/match-table-cxx.td (+62-62)
(modified) llvm/test/TableGen/GlobalISelEmitter/GlobalISelEmitter.td (+1-1)

diff --git a/llvm/docs/GlobalISel/GenericOpcode.rst b/llvm/docs/GlobalISel/GenericOpcode.rst
index a39994ca8f33d..1c60e7bbd7d62 100644
--- a/llvm/docs/GlobalISel/GenericOpcode.rst
+++ b/llvm/docs/GlobalISel/GenericOpcode.rst
@@ -148,6 +148,33 @@ G_EXTRACT for scalar types, but acts elementwise on vectors.
 
   %1:_(s16) = G_TRUNC %0:_(s32)
 
+G_TRUNC_SSAT_S
+^^^^^^^^^^^^^^
+
+Truncate a saturated signed input to a signed result.
+
+.. code-block:: none
+
+  %1:_(s16) = G_TRUNC_SSAT_S %0:_(s32)
+
+G_TRUNC_SSAT_U
+^^^^^^^^^^^^^^
+
+Truncate a saturated signed input to an unsigned result.
+
+.. code-block:: none
+
+  %1:_(s16) = G_TRUNC_SSAT_U %0:_(s32)
+
+G_TRUNC_USAT_U
+^^^^^^^^^^^^^^
+
+Truncate a saturated unsigned input to an unsigned result.
+
+.. code-block:: none
+
+  %1:_(s16) = G_TRUNC_USAT_U %0:_(s32)
+
 Type Conversions
 ----------------
 
diff --git a/llvm/include/llvm/CodeGen/GlobalISel/MachineIRBuilder.h b/llvm/include/llvm/CodeGen/GlobalISel/MachineIRBuilder.h
index 25fef99699fdf..ac12054d1a12f 100644
--- a/llvm/include/llvm/CodeGen/GlobalISel/MachineIRBuilder.h
+++ b/llvm/include/llvm/CodeGen/GlobalISel/MachineIRBuilder.h
@@ -809,6 +809,48 @@ class LLVM_ABI MachineIRBuilder {
   MachineInstrBuilder buildZExtInReg(const DstOp &Res, const SrcOp &Op,
                                      int64_t ImmOp);
 
+  /// Build and insert \p Res = \p G_TRUNC_SSAT_S \p Op
+  ///
+  /// G_TRUNC_SSAT_S truncates the saturated signed input, \p Op, to a signed
+  /// result.
+  ///  ///
+  /// \pre setBasicBlock or setMI must have been called.
+  /// \pre \p Res must be a generic virtual register with scalar or vector type.
+  /// \pre \p Op must be a generic virtual register with scalar or vector type.
+  ///
+  /// \return The newly created instruction.
+  MachineInstrBuilder buildTruncSSatS(const DstOp &Res, const SrcOp &Op) {
+    return buildInstr(TargetOpcode::G_TRUNC_SSAT_S, {Res}, {Op});
+  }
+
+  /// Build and insert \p Res = \p G_TRUNC_SSAT_U \p Op
+  ///
+  /// G_TRUNC_SSAT_U truncates the saturated signed input, \p Op, to a unsigned
+  /// result.
+  ///  ///
+  /// \pre setBasicBlock or setMI must have been called.
+  /// \pre \p Res must be a generic virtual register with scalar or vector type.
+  /// \pre \p Op must be a generic virtual register with scalar or vector type.
+  ///
+  /// \return The newly created instruction.
+  MachineInstrBuilder buildTruncSSatU(const DstOp &Res, const SrcOp &Op) {
+    return buildInstr(TargetOpcode::G_TRUNC_SSAT_U, {Res}, {Op});
+  }
+
+  /// Build and insert \p Res = \p G_TRUNC_USAT_U \p Op
+  ///
+  /// G_TRUNC_SSAT_S truncates the saturated unsigned input, \p Op, to a
+  /// unsigned result.
+  ///  ///
+  /// \pre setBasicBlock or setMI must have been called.
+  /// \pre \p Res must be a generic virtual register with scalar or vector type.
+  /// \pre \p Op must be a generic virtual register with scalar or vector type.
+  ///
+  /// \return The newly created instruction.
+  MachineInstrBuilder buildTruncUSatU(const DstOp &Res, const SrcOp &Op) {
+    return buildInstr(TargetOpcode::G_TRUNC_USAT_U, {Res}, {Op});
+  }
+
   /// Build and insert an appropriate cast between two registers of equal size.
   MachineInstrBuilder buildCast(const DstOp &Dst, const SrcOp &Src);
 
diff --git a/llvm/include/llvm/Support/TargetOpcodes.def b/llvm/include/llvm/Support/TargetOpcodes.def
index 92fd60e03112a..7fbc61231add6 100644
--- a/llvm/include/llvm/Support/TargetOpcodes.def
+++ b/llvm/include/llvm/Support/TargetOpcodes.def
@@ -475,6 +475,15 @@ HANDLE_TARGET_OPCODE(G_ANYEXT)
 /// elements of the vector.
 HANDLE_TARGET_OPCODE(G_TRUNC)
 
+/// Generic instruction to truncate a saturated signed operand to a signed result.
+HANDLE_TARGET_OPCODE(G_TRUNC_SSAT_S)
+
+/// Generic instruction to truncate a saturated signed operand to an unsigned result.
+HANDLE_TARGET_OPCODE(G_TRUNC_SSAT_U)
+
+/// Generic instruction to truncate a saturated unsigned operand to an unsigned result.
+HANDLE_TARGET_OPCODE(G_TRUNC_USAT_U)
+
 /// Generic integer constant.
 HANDLE_TARGET_OPCODE(G_CONSTANT)
 
diff --git a/llvm/include/llvm/Target/GenericOpcodes.td b/llvm/include/llvm/Target/GenericOpcodes.td
index a462b07461b41..e4db4d4f22119 100644
--- a/llvm/include/llvm/Target/GenericOpcodes.td
+++ b/llvm/include/llvm/Target/GenericOpcodes.td
@@ -86,6 +86,27 @@ def G_TRUNC : GenericInstruction {
   let hasSideEffects = false;
 }
 
+// Truncate the signed saturated operand to a signed result.
+def G_TRUNC_SSAT_S : GenericInstruction {
+  let OutOperandList = (outs type0:$dst);
+  let InOperandList = (ins type1:$src);
+  let hasSideEffects = false;
+}
+
+// Truncate the signed saturated operand to an unsigned result.
+def G_TRUNC_SSAT_U : GenericInstruction {
+  let OutOperandList = (outs type0:$dst);
+  let InOperandList = (ins type1:$src);
+  let hasSideEffects = false;
+}
+
+// Truncate the unsigned saturated operand to an unsigned result.
+def G_TRUNC_USAT_U : GenericInstruction {
+  let OutOperandList = (outs type0:$dst);
+  let InOperandList = (ins type1:$src);
+  let hasSideEffects = false;
+}
+
 def G_IMPLICIT_DEF : GenericInstruction {
   let OutOperandList = (outs type0:$dst);
   let InOperandList = (ins);
diff --git a/llvm/lib/CodeGen/MachineVerifier.cpp b/llvm/lib/CodeGen/MachineVerifier.cpp
index 109988246d0ab..01703fe09b79a 100644
--- a/llvm/lib/CodeGen/MachineVerifier.cpp
+++ b/llvm/lib/CodeGen/MachineVerifier.cpp
@@ -1424,6 +1424,9 @@ void MachineVerifier::verifyPreISelGenericInstruction(const MachineInstr *MI) {
   case TargetOpcode::G_ZEXT:
   case TargetOpcode::G_ANYEXT:
   case TargetOpcode::G_TRUNC:
+  case TargetOpcode::G_TRUNC_SSAT_S:
+  case TargetOpcode::G_TRUNC_SSAT_U:
+  case TargetOpcode::G_TRUNC_USAT_U:
   case TargetOpcode::G_FPEXT:
   case TargetOpcode::G_FPTRUNC: {
     // Number of operands and presense of types is already checked (and
@@ -1450,6 +1453,9 @@ void MachineVerifier::verifyPreISelGenericInstruction(const MachineInstr *MI) {
         report("Generic extend has destination type no larger than source", MI);
       break;
     case TargetOpcode::G_TRUNC:
+    case TargetOpcode::G_TRUNC_SSAT_S:
+    case TargetOpcode::G_TRUNC_SSAT_U:
+    case TargetOpcode::G_TRUNC_USAT_U:
     case TargetOpcode::G_FPTRUNC:
       if (DstSize >= SrcSize)
         report("Generic truncate has destination type no smaller than source",
diff --git a/llvm/test/CodeGen/AArch64/GlobalISel/legalizer-info-validation.mir b/llvm/test/CodeGen/AArch64/GlobalISel/legalizer-info-validation.mir
index a96ef2a0faab3..d0424f2e400fc 100644
--- a/llvm/test/CodeGen/AArch64/GlobalISel/legalizer-info-validation.mir
+++ b/llvm/test/CodeGen/AArch64/GlobalISel/legalizer-info-validation.mir
@@ -319,6 +319,15 @@
 # DEBUG-NEXT: G_TRUNC (opcode {{[0-9]+}}): 2 type indices, 0 imm indices
 # DEBUG-NEXT: .. type index coverage check SKIPPED: user-defined predicate detected
 # DEBUG-NEXT: .. imm index coverage check SKIPPED: user-defined predicate detected
+# DEBUG-NEXT: G_TRUNC_SSAT_S (opcode {{[0-9]+}}): 2 type indices, 0 imm indices
+# DEBUG-NEXT: .. type index coverage check SKIPPED: no rules defined
+# DEBUG-NEXT: .. imm index coverage check SKIPPED: no rules defined
+# DEBUG-NEXT: G_TRUNC_SSAT_U (opcode {{[0-9]+}}): 2 type indices, 0 imm indices
+# DEBUG-NEXT: .. type index coverage check SKIPPED: no rules defined
+# DEBUG-NEXT: .. imm index coverage check SKIPPED: no rules defined
+# DEBUG-NEXT: G_TRUNC_USAT_U (opcode {{[0-9]+}}): 2 type indices, 0 imm indices
+# DEBUG-NEXT: .. type index coverage check SKIPPED: no rules defined
+# DEBUG-NEXT: .. imm index coverage check SKIPPED: no rules defined
 # DEBUG-NEXT: G_CONSTANT (opcode {{[0-9]+}}): 1 type index, 0 imm indices
 # DEBUG-NEXT: .. the first uncovered type index: 1, OK
 # DEBUG-NEXT: .. the first uncovered imm index: 0, OK
diff --git a/llvm/test/CodeGen/RISCV/GlobalISel/legalizer-info-validation.mir b/llvm/test/CodeGen/RISCV/GlobalISel/legalizer-info-validation.mir
index d41d3f76436cc..30e455f57737b 100644
--- a/llvm/test/CodeGen/RISCV/GlobalISel/legalizer-info-validation.mir
+++ b/llvm/test/CodeGen/RISCV/GlobalISel/legalizer-info-validation.mir
@@ -315,6 +315,15 @@
 # DEBUG-NEXT: G_TRUNC (opcode {{[0-9]+}}): 2 type indices, 0 imm indices
 # DEBUG-NEXT: .. type index coverage check SKIPPED: no rules defined
 # DEBUG-NEXT: .. imm index coverage check SKIPPED: no rules defined
+# DEBUG-NEXT: G_TRUNC_SSAT_S (opcode {{[0-9]+}}): 2 type indices, 0 imm indices
+# DEBUG-NEXT: .. type index coverage check SKIPPED: no rules defined
+# DEBUG-NEXT: .. imm index coverage check SKIPPED: no rules defined
+# DEBUG-NEXT: G_TRUNC_SSAT_U (opcode {{[0-9]+}}): 2 type indices, 0 imm indices
+# DEBUG-NEXT: .. type index coverage check SKIPPED: no rules defined
+# DEBUG-NEXT: .. imm index coverage check SKIPPED: no rules defined
+# DEBUG-NEXT: G_TRUNC_USAT_U (opcode {{[0-9]+}}): 2 type indices, 0 imm indices
+# DEBUG-NEXT: .. type index coverage check SKIPPED: no rules defined
+# DEBUG-NEXT: .. imm index coverage check SKIPPED: no rules defined
 # DEBUG-NEXT: G_CONSTANT (opcode {{[0-9]+}}): 1 type index, 0 imm indices
 # DEBUG-NEXT: .. the first uncovered type index: 1, OK
 # DEBUG-NEXT: .. the first uncovered imm index: 0, OK
diff --git a/llvm/test/MC/ELF/mc-dump.s b/llvm/test/MC/ELF/mc-dump.s
index 9c31daed3450b..972e5befb83f5 100644
--- a/llvm/test/MC/ELF/mc-dump.s
+++ b/llvm/test/MC/ELF/mc-dump.s
@@ -12,7 +12,7 @@
 # CHECK-NEXT:0 Data Size:0 []
 # CHECK-NEXT:  Symbol @0 _start
 # CHECK-NEXT:0 Org Offset:3 Value:0
-# CHECK-NEXT:3 Relaxable Size:2 <MCInst #1996 <MCOperand Expr:.Ltmp0>>
+# CHECK-NEXT:3 Relaxable Size:2 <MCInst #1999 <MCOperand Expr:.Ltmp0>>
 # CHECK-NEXT:  Fixup @1 Value:.Ltmp0-1 Kind:4001
 # CHECK-NEXT:5 Data Size:16 [48,8b,04,25,00,00,00,00,48,8b,04,25,00,00,00,00]
 # CHECK-NEXT:  Fixup @4 Value:f0@<variant 11> Kind:4017
diff --git a/llvm/test/TableGen/GlobalISelCombinerEmitter/match-table-cxx.td b/llvm/test/TableGen/GlobalISelCombinerEmitter/match-table-cxx.td
index dfb2c173f2c88..ce4f0108b4843 100644
--- a/llvm/test/TableGen/GlobalISelCombinerEmitter/match-table-cxx.td
+++ b/llvm/test/TableGen/GlobalISelCombinerEmitter/match-table-cxx.td
@@ -96,71 +96,71 @@ def MyCombiner: GICombiner<"GenMyCombiner", [
 
 // CHECK:      const uint8_t *GenMyCombiner::getMatchTable() const {
 // CHECK-NEXT:   constexpr static uint8_t MatchTable0[] = {
-// CHECK-NEXT:      /*   0 */ GIM_SwitchOpcode, /*MI*/0, /*[*/GIMT_Encode2(99), GIMT_Encode2(207), /*)*//*default:*//*Label 5*/ GIMT_Encode4(508),
-// CHECK-NEXT:      /*  10 */ /*TargetOpcode::G_STORE*//*Label 0*/ GIMT_Encode4(442), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0),
-// CHECK-NEXT:      /* 170 */ /*TargetOpcode::G_SEXT*//*Label 1*/ GIMT_Encode4(460), GIMT_Encode4(0),
-// CHECK-NEXT:      /* 178 */ /*TargetOpcode::G_ZEXT*//*Label 2*/ GIMT_Encode4(472), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0),
-// CHECK-NEXT:      /* 402 */ /*TargetOpcode::G_FNEG*//*Label 3*/ GIMT_Encode4(484), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0),
-// CHECK-NEXT:      /* 438 */ /*TargetOpcode::G_FABS*//*Label 4*/ GIMT_Encode4(496),
-// CHECK-NEXT:      /* 442 */ // Label 0: @442
-// CHECK-NEXT:      /* 442 */ GIM_Try, /*On fail goto*//*Label 6*/ GIMT_Encode4(459), // Rule ID 2 //
-// CHECK-NEXT:      /* 447 */   GIM_CheckSimplePredicate, GIMT_Encode2(GICXXPred_Simple_IsRule2Enabled),
-// CHECK-NEXT:      /* 450 */   // MIs[0] x
-// CHECK-NEXT:      /* 450 */   // No operand predicates
-// CHECK-NEXT:      /* 450 */   // MIs[0] y
-// CHECK-NEXT:      /* 450 */   // No operand predicates
-// CHECK-NEXT:      /* 450 */   GIM_CheckCxxInsnPredicate, /*MI*/0, /*FnId*/GIMT_Encode2(GICXXPred_MI_Predicate_GICombiner0),
-// CHECK-NEXT:      /* 454 */   GIM_CheckCxxInsnPredicate, /*MI*/0, /*FnId*/GIMT_Encode2(GICXXPred_MI_Predicate_GICombiner1),
-// CHECK-NEXT:      /* 458 */   // Combiner Rule #2: TwoMatchNoApply
-// CHECK-NEXT:      /* 458 */   GIR_EraseRootFromParent_Done,
-// CHECK-NEXT:      /* 459 */ // Label 6: @459
-// CHECK-NEXT:      /* 459 */ GIM_Reject,
-// CHECK-NEXT:      /* 460 */ // Label 1: @460
-// CHECK-NEXT:      /* 460 */ GIM_Try, /*On fail goto*//*Label 7*/ GIMT_Encode4(471), // Rule ID 3 //
-// CHECK-NEXT:      /* 465 */   GIM_CheckSimplePredicate, GIMT_Encode2(GICXXPred_Simple_IsRule3Enabled),
-// CHECK-NEXT:      /* 468 */   // MIs[0] a
-// CHECK-NEXT:      /* 468 */   // No operand predicates
-// CHECK-NEXT:      /* 468 */   // MIs[0] y
-// CHECK-NEXT:      /* 468 */   // No operand predicates
-// CHECK-NEXT:      /* 468 */   // Combiner Rule #3: NoMatchTwoApply
-// CHECK-NEXT:      /* 468 */   GIR_DoneWithCustomAction, /*Fn*/GIMT_Encode2(GICXXCustomAction_GICombiner2),
-// CHECK-NEXT:      /* 471 */ // Label 7: @471
+// CHECK-NEXT:      /*   0 */ GIM_SwitchOpcode, /*MI*/0, /*[*/GIMT_Encode2(99), GIMT_Encode2(210), /*)*//*default:*//*Label 5*/ GIMT_Encode4(520),
+// CHECK-NEXT:      /* 10 */ /*TargetOpcode::G_STORE*//*Label 0*/ GIMT_Encode4(454), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0),
+// CHECK-NEXT:      /* 182 */ /*TargetOpcode::G_SEXT*//*Label 1*/ GIMT_Encode4(472), GIMT_Encode4(0),
+// CHECK-NEXT:      /* 190 */ /*TargetOpcode::G_ZEXT*//*Label 2*/ GIMT_Encode4(484), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0),
+// CHECK-NEXT:      /* 414 */ /*TargetOpcode::G_FNEG*//*Label 3*/ GIMT_Encode4(496), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0),
+// CHECK-NEXT:      /* 450 */ /*TargetOpcode::G_FABS*//*Label 4*/ GIMT_Encode4(508),
+// CHECK-NEXT:      /* 454 */ // Label 0: @454
+// CHECK-NEXT:      /* 454 */ GIM_Try, /*On fail goto*//*Label 6*/ GIMT_Encode4(471), // Rule ID 2 //
+// CHECK-NEXT:      /* 459 */ GIM_CheckSimplePredicate, GIMT_Encode2(GICXXPred_Simple_IsRule2Enabled),
+// CHECK-NEXT:      /* 462 */ // MIs[0] x
+// CHECK-NEXT:      /* 462 */ // No operand predicates
+// CHECK-NEXT:      /* 462 */ // MIs[0] y
+// CHECK-NEXT:      /* 462 */ // No operand predicates
+// CHECK-NEXT:      /* 462 */ GIM_CheckCxxInsnPredicate, /*MI*/0, /*FnId*/GIMT_Encode2(GICXXPred_MI_Predicate_GICombiner0),
+// CHECK-NEXT:      /* 466 */ GIM_CheckCxxInsnPredicate, /*MI*/0, /*FnId*/GIMT_Encode2(GICXXPred_MI_Predicate_GICombiner1),
+// CHECK-NEXT:      /* 470 */ // Combiner Rule #2: TwoMatchNoApply
+// CHECK-NEXT:      /* 470 */ GIR_EraseRootFromParent_Done,
+// CHECK-NEXT:      /* 471 */ // Label 6: @471
 // CHECK-NEXT:      /* 471 */ GIM_Reject,
-// CHECK-NEXT:      /* 472 */ // Label 2: @472
-// CHECK-NEXT:      /* 472 */ GIM_Try, /*On fail goto*//*Label 8*/ GIMT_Encode4(483), // Rule ID 4 //
-// CHECK-NEXT:      /* 477 */   GIM_CheckSimplePredicate, GIMT_Encode2(GICXXPred_Simple_IsRule4Enabled),
-// CHECK-NEXT:      /* 480 */   // MIs[0] a
-// CHECK-NEXT:      /* 480 */   // No operand predicates
-// CHECK-NEXT:      /* 480 */   // MIs[0] y
-// CHECK-NEXT:      /* 480 */   // No operand predicates
-// CHECK-NEXT:      /* 480 */   // Combiner Rule #4: CombineCXXOrder
-// CHECK-NEXT:      /* 480 */   GIR_DoneWithCustomAction, /*Fn*/GIMT_Encode2(GICXXCustomAction_GICombiner3),
-// CHECK-NEXT:      /* 483 */ // Label 8: @483
+// CHECK-NEXT:      /* 472 */ // Label 1: @472
+// CHECK-NEXT:      /* 472 */ GIM_Try, /*On fail goto*//*Label 7*/ GIMT_Encode4(483), // Rule ID 3 //
+// CHECK-NEXT:      /* 477 */ GIM_CheckSimplePredicate, GIMT_Encode2(GICXXPred_Simple_IsRule3Enabled),
+// CHECK-NEXT:      /* 480 */ // MIs[0] a
+// CHECK-NEXT:      /* 480 */ // No operand predicates
+// CHECK-NEXT:      /* 480 */ // MIs[0] y
+// CHECK-NEXT:      /* 480 */ // No operand predicates
+// CHECK-NEXT:      /* 480 */ // Combiner Rule #3: NoMatchTwoApply
+// CHECK-NEXT:      /* 480 */ GIR_DoneWithCustomAction, /*Fn*/GIMT_Encode2(GICXXCustomAction_GICombiner2),
+// CHECK-NEXT:      /* 483 */ // Label 7: @483
 // CHECK-NEXT:      /* 483 */ GIM_Reject,
-// CHECK-NEXT:      /* 484 */ // Label 3: @484
-// CHECK-NEXT:      /* 484 */ GIM_Try, /*On fail goto*//*Label 9*/ GIMT_Encode4(495), // Rule ID 1 //
-// CHECK-NEXT:      /* 489 */   GIM_CheckSimplePredicate, GIMT_Encode2(GICXXPred_Simple_IsRule1Enabled),
-// CHECK-NEXT:      /* 492 */   // MIs[0] a
-// CHECK-NEXT:      /* 492 */   // No operand predicates
-// CHECK-NEXT:      /* 492 */   // MIs[0] b
-// CHECK-NEXT:      /* 492 */   // No operand predicates
-// CHECK-NEXT:      /* 492 */   // Combiner Rule #1: TwoMatchTwoApply
-// CHECK-NEXT:      /* 492 */   GIR_DoneWithCustomAction, /*Fn*/GIMT_Encode2(GICXXCustomAction_GICombiner1),
-// CHECK-NEXT:      /* 495 */ // Label 9: @495
+// CHECK-NEXT:      /* 484 */ // Label 2: @484
+// CHECK-NEXT:      /* 484 */ GIM_Try, /*On fail goto*//*Label 8*/ GIMT_Encode4(495), // Rule ID 4 //
+// CHECK-NEXT:      /* 489 */ GIM_CheckSimplePredicate, GIMT_Encode2(GICXXPred_Simple_IsRule4Enabled),
+// CHECK-NEXT:      /* 492 */ // MIs[0] a
+// CHECK-NEXT:      /* 492 */ // No operand predicates
+// CHECK-NEXT:      /* 492 */ // MIs[0] y
+// CHECK-NEXT:      /* 492 */ // No operand predicates
+// CHECK-NEXT:      /* 492 */ // Combiner Rule #4: CombineCXXOrder
+// CHECK-NEXT:      /* 492 */ GIR_DoneWithCustomAction, /*Fn*/GIMT_Encode2(GICXXCustomAction_GICombiner3),
+// CHECK-NEXT:      /* 495 */ // Label 8: @495
 // CHECK-NEXT:      /* 495 */ GIM_Reject,
-// CHECK...
[truncated]

llvmbot · 2025-07-08T13:51:56Z

@llvm/pr-subscribers-llvm-globalisel

Author: None (jyli0116)

Changes

Introduces saturated truncate instructions to Global ISel: G_TRUNC_SSAT_S, G_TRUNC_SSAT_U, G_TRUNC_USAT_U. These were previously introduced to SDAG to reduce redundant code.

The patch only initially introduces the instruction, a later patch will follow to add combines and legalization for each instruction.

Patch is 23.10 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/147526.diff

10 Files Affected:

(modified) llvm/docs/GlobalISel/GenericOpcode.rst (+27)
(modified) llvm/include/llvm/CodeGen/GlobalISel/MachineIRBuilder.h (+42)
(modified) llvm/include/llvm/Support/TargetOpcodes.def (+9)
(modified) llvm/include/llvm/Target/GenericOpcodes.td (+21)
(modified) llvm/lib/CodeGen/MachineVerifier.cpp (+6)
(modified) llvm/test/CodeGen/AArch64/GlobalISel/legalizer-info-validation.mir (+9)
(modified) llvm/test/CodeGen/RISCV/GlobalISel/legalizer-info-validation.mir (+9)
(modified) llvm/test/MC/ELF/mc-dump.s (+1-1)
(modified) llvm/test/TableGen/GlobalISelCombinerEmitter/match-table-cxx.td (+62-62)
(modified) llvm/test/TableGen/GlobalISelEmitter/GlobalISelEmitter.td (+1-1)

diff --git a/llvm/docs/GlobalISel/GenericOpcode.rst b/llvm/docs/GlobalISel/GenericOpcode.rst
index a39994ca8f33d..1c60e7bbd7d62 100644
--- a/llvm/docs/GlobalISel/GenericOpcode.rst
+++ b/llvm/docs/GlobalISel/GenericOpcode.rst
@@ -148,6 +148,33 @@ G_EXTRACT for scalar types, but acts elementwise on vectors.
 
   %1:_(s16) = G_TRUNC %0:_(s32)
 
+G_TRUNC_SSAT_S
+^^^^^^^^^^^^^^
+
+Truncate a saturated signed input to a signed result.
+
+.. code-block:: none
+
+  %1:_(s16) = G_TRUNC_SSAT_S %0:_(s32)
+
+G_TRUNC_SSAT_U
+^^^^^^^^^^^^^^
+
+Truncate a saturated signed input to an unsigned result.
+
+.. code-block:: none
+
+  %1:_(s16) = G_TRUNC_SSAT_U %0:_(s32)
+
+G_TRUNC_USAT_U
+^^^^^^^^^^^^^^
+
+Truncate a saturated unsigned input to an unsigned result.
+
+.. code-block:: none
+
+  %1:_(s16) = G_TRUNC_USAT_U %0:_(s32)
+
 Type Conversions
 ----------------
 
diff --git a/llvm/include/llvm/CodeGen/GlobalISel/MachineIRBuilder.h b/llvm/include/llvm/CodeGen/GlobalISel/MachineIRBuilder.h
index 25fef99699fdf..ac12054d1a12f 100644
--- a/llvm/include/llvm/CodeGen/GlobalISel/MachineIRBuilder.h
+++ b/llvm/include/llvm/CodeGen/GlobalISel/MachineIRBuilder.h
@@ -809,6 +809,48 @@ class LLVM_ABI MachineIRBuilder {
   MachineInstrBuilder buildZExtInReg(const DstOp &Res, const SrcOp &Op,
                                      int64_t ImmOp);
 
+  /// Build and insert \p Res = \p G_TRUNC_SSAT_S \p Op
+  ///
+  /// G_TRUNC_SSAT_S truncates the saturated signed input, \p Op, to a signed
+  /// result.
+  ///  ///
+  /// \pre setBasicBlock or setMI must have been called.
+  /// \pre \p Res must be a generic virtual register with scalar or vector type.
+  /// \pre \p Op must be a generic virtual register with scalar or vector type.
+  ///
+  /// \return The newly created instruction.
+  MachineInstrBuilder buildTruncSSatS(const DstOp &Res, const SrcOp &Op) {
+    return buildInstr(TargetOpcode::G_TRUNC_SSAT_S, {Res}, {Op});
+  }
+
+  /// Build and insert \p Res = \p G_TRUNC_SSAT_U \p Op
+  ///
+  /// G_TRUNC_SSAT_U truncates the saturated signed input, \p Op, to a unsigned
+  /// result.
+  ///  ///
+  /// \pre setBasicBlock or setMI must have been called.
+  /// \pre \p Res must be a generic virtual register with scalar or vector type.
+  /// \pre \p Op must be a generic virtual register with scalar or vector type.
+  ///
+  /// \return The newly created instruction.
+  MachineInstrBuilder buildTruncSSatU(const DstOp &Res, const SrcOp &Op) {
+    return buildInstr(TargetOpcode::G_TRUNC_SSAT_U, {Res}, {Op});
+  }
+
+  /// Build and insert \p Res = \p G_TRUNC_USAT_U \p Op
+  ///
+  /// G_TRUNC_SSAT_S truncates the saturated unsigned input, \p Op, to a
+  /// unsigned result.
+  ///  ///
+  /// \pre setBasicBlock or setMI must have been called.
+  /// \pre \p Res must be a generic virtual register with scalar or vector type.
+  /// \pre \p Op must be a generic virtual register with scalar or vector type.
+  ///
+  /// \return The newly created instruction.
+  MachineInstrBuilder buildTruncUSatU(const DstOp &Res, const SrcOp &Op) {
+    return buildInstr(TargetOpcode::G_TRUNC_USAT_U, {Res}, {Op});
+  }
+
   /// Build and insert an appropriate cast between two registers of equal size.
   MachineInstrBuilder buildCast(const DstOp &Dst, const SrcOp &Src);
 
diff --git a/llvm/include/llvm/Support/TargetOpcodes.def b/llvm/include/llvm/Support/TargetOpcodes.def
index 92fd60e03112a..7fbc61231add6 100644
--- a/llvm/include/llvm/Support/TargetOpcodes.def
+++ b/llvm/include/llvm/Support/TargetOpcodes.def
@@ -475,6 +475,15 @@ HANDLE_TARGET_OPCODE(G_ANYEXT)
 /// elements of the vector.
 HANDLE_TARGET_OPCODE(G_TRUNC)
 
+/// Generic instruction to truncate a saturated signed operand to a signed result.
+HANDLE_TARGET_OPCODE(G_TRUNC_SSAT_S)
+
+/// Generic instruction to truncate a saturated signed operand to an unsigned result.
+HANDLE_TARGET_OPCODE(G_TRUNC_SSAT_U)
+
+/// Generic instruction to truncate a saturated unsigned operand to an unsigned result.
+HANDLE_TARGET_OPCODE(G_TRUNC_USAT_U)
+
 /// Generic integer constant.
 HANDLE_TARGET_OPCODE(G_CONSTANT)
 
diff --git a/llvm/include/llvm/Target/GenericOpcodes.td b/llvm/include/llvm/Target/GenericOpcodes.td
index a462b07461b41..e4db4d4f22119 100644
--- a/llvm/include/llvm/Target/GenericOpcodes.td
+++ b/llvm/include/llvm/Target/GenericOpcodes.td
@@ -86,6 +86,27 @@ def G_TRUNC : GenericInstruction {
   let hasSideEffects = false;
 }
 
+// Truncate the signed saturated operand to a signed result.
+def G_TRUNC_SSAT_S : GenericInstruction {
+  let OutOperandList = (outs type0:$dst);
+  let InOperandList = (ins type1:$src);
+  let hasSideEffects = false;
+}
+
+// Truncate the signed saturated operand to an unsigned result.
+def G_TRUNC_SSAT_U : GenericInstruction {
+  let OutOperandList = (outs type0:$dst);
+  let InOperandList = (ins type1:$src);
+  let hasSideEffects = false;
+}
+
+// Truncate the unsigned saturated operand to an unsigned result.
+def G_TRUNC_USAT_U : GenericInstruction {
+  let OutOperandList = (outs type0:$dst);
+  let InOperandList = (ins type1:$src);
+  let hasSideEffects = false;
+}
+
 def G_IMPLICIT_DEF : GenericInstruction {
   let OutOperandList = (outs type0:$dst);
   let InOperandList = (ins);
diff --git a/llvm/lib/CodeGen/MachineVerifier.cpp b/llvm/lib/CodeGen/MachineVerifier.cpp
index 109988246d0ab..01703fe09b79a 100644
--- a/llvm/lib/CodeGen/MachineVerifier.cpp
+++ b/llvm/lib/CodeGen/MachineVerifier.cpp
@@ -1424,6 +1424,9 @@ void MachineVerifier::verifyPreISelGenericInstruction(const MachineInstr *MI) {
   case TargetOpcode::G_ZEXT:
   case TargetOpcode::G_ANYEXT:
   case TargetOpcode::G_TRUNC:
+  case TargetOpcode::G_TRUNC_SSAT_S:
+  case TargetOpcode::G_TRUNC_SSAT_U:
+  case TargetOpcode::G_TRUNC_USAT_U:
   case TargetOpcode::G_FPEXT:
   case TargetOpcode::G_FPTRUNC: {
     // Number of operands and presense of types is already checked (and
@@ -1450,6 +1453,9 @@ void MachineVerifier::verifyPreISelGenericInstruction(const MachineInstr *MI) {
         report("Generic extend has destination type no larger than source", MI);
       break;
     case TargetOpcode::G_TRUNC:
+    case TargetOpcode::G_TRUNC_SSAT_S:
+    case TargetOpcode::G_TRUNC_SSAT_U:
+    case TargetOpcode::G_TRUNC_USAT_U:
     case TargetOpcode::G_FPTRUNC:
       if (DstSize >= SrcSize)
         report("Generic truncate has destination type no smaller than source",
diff --git a/llvm/test/CodeGen/AArch64/GlobalISel/legalizer-info-validation.mir b/llvm/test/CodeGen/AArch64/GlobalISel/legalizer-info-validation.mir
index a96ef2a0faab3..d0424f2e400fc 100644
--- a/llvm/test/CodeGen/AArch64/GlobalISel/legalizer-info-validation.mir
+++ b/llvm/test/CodeGen/AArch64/GlobalISel/legalizer-info-validation.mir
@@ -319,6 +319,15 @@
 # DEBUG-NEXT: G_TRUNC (opcode {{[0-9]+}}): 2 type indices, 0 imm indices
 # DEBUG-NEXT: .. type index coverage check SKIPPED: user-defined predicate detected
 # DEBUG-NEXT: .. imm index coverage check SKIPPED: user-defined predicate detected
+# DEBUG-NEXT: G_TRUNC_SSAT_S (opcode {{[0-9]+}}): 2 type indices, 0 imm indices
+# DEBUG-NEXT: .. type index coverage check SKIPPED: no rules defined
+# DEBUG-NEXT: .. imm index coverage check SKIPPED: no rules defined
+# DEBUG-NEXT: G_TRUNC_SSAT_U (opcode {{[0-9]+}}): 2 type indices, 0 imm indices
+# DEBUG-NEXT: .. type index coverage check SKIPPED: no rules defined
+# DEBUG-NEXT: .. imm index coverage check SKIPPED: no rules defined
+# DEBUG-NEXT: G_TRUNC_USAT_U (opcode {{[0-9]+}}): 2 type indices, 0 imm indices
+# DEBUG-NEXT: .. type index coverage check SKIPPED: no rules defined
+# DEBUG-NEXT: .. imm index coverage check SKIPPED: no rules defined
 # DEBUG-NEXT: G_CONSTANT (opcode {{[0-9]+}}): 1 type index, 0 imm indices
 # DEBUG-NEXT: .. the first uncovered type index: 1, OK
 # DEBUG-NEXT: .. the first uncovered imm index: 0, OK
diff --git a/llvm/test/CodeGen/RISCV/GlobalISel/legalizer-info-validation.mir b/llvm/test/CodeGen/RISCV/GlobalISel/legalizer-info-validation.mir
index d41d3f76436cc..30e455f57737b 100644
--- a/llvm/test/CodeGen/RISCV/GlobalISel/legalizer-info-validation.mir
+++ b/llvm/test/CodeGen/RISCV/GlobalISel/legalizer-info-validation.mir
@@ -315,6 +315,15 @@
 # DEBUG-NEXT: G_TRUNC (opcode {{[0-9]+}}): 2 type indices, 0 imm indices
 # DEBUG-NEXT: .. type index coverage check SKIPPED: no rules defined
 # DEBUG-NEXT: .. imm index coverage check SKIPPED: no rules defined
+# DEBUG-NEXT: G_TRUNC_SSAT_S (opcode {{[0-9]+}}): 2 type indices, 0 imm indices
+# DEBUG-NEXT: .. type index coverage check SKIPPED: no rules defined
+# DEBUG-NEXT: .. imm index coverage check SKIPPED: no rules defined
+# DEBUG-NEXT: G_TRUNC_SSAT_U (opcode {{[0-9]+}}): 2 type indices, 0 imm indices
+# DEBUG-NEXT: .. type index coverage check SKIPPED: no rules defined
+# DEBUG-NEXT: .. imm index coverage check SKIPPED: no rules defined
+# DEBUG-NEXT: G_TRUNC_USAT_U (opcode {{[0-9]+}}): 2 type indices, 0 imm indices
+# DEBUG-NEXT: .. type index coverage check SKIPPED: no rules defined
+# DEBUG-NEXT: .. imm index coverage check SKIPPED: no rules defined
 # DEBUG-NEXT: G_CONSTANT (opcode {{[0-9]+}}): 1 type index, 0 imm indices
 # DEBUG-NEXT: .. the first uncovered type index: 1, OK
 # DEBUG-NEXT: .. the first uncovered imm index: 0, OK
diff --git a/llvm/test/MC/ELF/mc-dump.s b/llvm/test/MC/ELF/mc-dump.s
index 9c31daed3450b..972e5befb83f5 100644
--- a/llvm/test/MC/ELF/mc-dump.s
+++ b/llvm/test/MC/ELF/mc-dump.s
@@ -12,7 +12,7 @@
 # CHECK-NEXT:0 Data Size:0 []
 # CHECK-NEXT:  Symbol @0 _start
 # CHECK-NEXT:0 Org Offset:3 Value:0
-# CHECK-NEXT:3 Relaxable Size:2 <MCInst #1996 <MCOperand Expr:.Ltmp0>>
+# CHECK-NEXT:3 Relaxable Size:2 <MCInst #1999 <MCOperand Expr:.Ltmp0>>
 # CHECK-NEXT:  Fixup @1 Value:.Ltmp0-1 Kind:4001
 # CHECK-NEXT:5 Data Size:16 [48,8b,04,25,00,00,00,00,48,8b,04,25,00,00,00,00]
 # CHECK-NEXT:  Fixup @4 Value:f0@<variant 11> Kind:4017
diff --git a/llvm/test/TableGen/GlobalISelCombinerEmitter/match-table-cxx.td b/llvm/test/TableGen/GlobalISelCombinerEmitter/match-table-cxx.td
index dfb2c173f2c88..ce4f0108b4843 100644
--- a/llvm/test/TableGen/GlobalISelCombinerEmitter/match-table-cxx.td
+++ b/llvm/test/TableGen/GlobalISelCombinerEmitter/match-table-cxx.td
@@ -96,71 +96,71 @@ def MyCombiner: GICombiner<"GenMyCombiner", [
 
 // CHECK:      const uint8_t *GenMyCombiner::getMatchTable() const {
 // CHECK-NEXT:   constexpr static uint8_t MatchTable0[] = {
-// CHECK-NEXT:      /*   0 */ GIM_SwitchOpcode, /*MI*/0, /*[*/GIMT_Encode2(99), GIMT_Encode2(207), /*)*//*default:*//*Label 5*/ GIMT_Encode4(508),
-// CHECK-NEXT:      /*  10 */ /*TargetOpcode::G_STORE*//*Label 0*/ GIMT_Encode4(442), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0),
-// CHECK-NEXT:      /* 170 */ /*TargetOpcode::G_SEXT*//*Label 1*/ GIMT_Encode4(460), GIMT_Encode4(0),
-// CHECK-NEXT:      /* 178 */ /*TargetOpcode::G_ZEXT*//*Label 2*/ GIMT_Encode4(472), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0),
-// CHECK-NEXT:      /* 402 */ /*TargetOpcode::G_FNEG*//*Label 3*/ GIMT_Encode4(484), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0),
-// CHECK-NEXT:      /* 438 */ /*TargetOpcode::G_FABS*//*Label 4*/ GIMT_Encode4(496),
-// CHECK-NEXT:      /* 442 */ // Label 0: @442
-// CHECK-NEXT:      /* 442 */ GIM_Try, /*On fail goto*//*Label 6*/ GIMT_Encode4(459), // Rule ID 2 //
-// CHECK-NEXT:      /* 447 */   GIM_CheckSimplePredicate, GIMT_Encode2(GICXXPred_Simple_IsRule2Enabled),
-// CHECK-NEXT:      /* 450 */   // MIs[0] x
-// CHECK-NEXT:      /* 450 */   // No operand predicates
-// CHECK-NEXT:      /* 450 */   // MIs[0] y
-// CHECK-NEXT:      /* 450 */   // No operand predicates
-// CHECK-NEXT:      /* 450 */   GIM_CheckCxxInsnPredicate, /*MI*/0, /*FnId*/GIMT_Encode2(GICXXPred_MI_Predicate_GICombiner0),
-// CHECK-NEXT:      /* 454 */   GIM_CheckCxxInsnPredicate, /*MI*/0, /*FnId*/GIMT_Encode2(GICXXPred_MI_Predicate_GICombiner1),
-// CHECK-NEXT:      /* 458 */   // Combiner Rule #2: TwoMatchNoApply
-// CHECK-NEXT:      /* 458 */   GIR_EraseRootFromParent_Done,
-// CHECK-NEXT:      /* 459 */ // Label 6: @459
-// CHECK-NEXT:      /* 459 */ GIM_Reject,
-// CHECK-NEXT:      /* 460 */ // Label 1: @460
-// CHECK-NEXT:      /* 460 */ GIM_Try, /*On fail goto*//*Label 7*/ GIMT_Encode4(471), // Rule ID 3 //
-// CHECK-NEXT:      /* 465 */   GIM_CheckSimplePredicate, GIMT_Encode2(GICXXPred_Simple_IsRule3Enabled),
-// CHECK-NEXT:      /* 468 */   // MIs[0] a
-// CHECK-NEXT:      /* 468 */   // No operand predicates
-// CHECK-NEXT:      /* 468 */   // MIs[0] y
-// CHECK-NEXT:      /* 468 */   // No operand predicates
-// CHECK-NEXT:      /* 468 */   // Combiner Rule #3: NoMatchTwoApply
-// CHECK-NEXT:      /* 468 */   GIR_DoneWithCustomAction, /*Fn*/GIMT_Encode2(GICXXCustomAction_GICombiner2),
-// CHECK-NEXT:      /* 471 */ // Label 7: @471
+// CHECK-NEXT:      /*   0 */ GIM_SwitchOpcode, /*MI*/0, /*[*/GIMT_Encode2(99), GIMT_Encode2(210), /*)*//*default:*//*Label 5*/ GIMT_Encode4(520),
+// CHECK-NEXT:      /* 10 */ /*TargetOpcode::G_STORE*//*Label 0*/ GIMT_Encode4(454), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0),
+// CHECK-NEXT:      /* 182 */ /*TargetOpcode::G_SEXT*//*Label 1*/ GIMT_Encode4(472), GIMT_Encode4(0),
+// CHECK-NEXT:      /* 190 */ /*TargetOpcode::G_ZEXT*//*Label 2*/ GIMT_Encode4(484), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0),
+// CHECK-NEXT:      /* 414 */ /*TargetOpcode::G_FNEG*//*Label 3*/ GIMT_Encode4(496), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0), GIMT_Encode4(0),
+// CHECK-NEXT:      /* 450 */ /*TargetOpcode::G_FABS*//*Label 4*/ GIMT_Encode4(508),
+// CHECK-NEXT:      /* 454 */ // Label 0: @454
+// CHECK-NEXT:      /* 454 */ GIM_Try, /*On fail goto*//*Label 6*/ GIMT_Encode4(471), // Rule ID 2 //
+// CHECK-NEXT:      /* 459 */ GIM_CheckSimplePredicate, GIMT_Encode2(GICXXPred_Simple_IsRule2Enabled),
+// CHECK-NEXT:      /* 462 */ // MIs[0] x
+// CHECK-NEXT:      /* 462 */ // No operand predicates
+// CHECK-NEXT:      /* 462 */ // MIs[0] y
+// CHECK-NEXT:      /* 462 */ // No operand predicates
+// CHECK-NEXT:      /* 462 */ GIM_CheckCxxInsnPredicate, /*MI*/0, /*FnId*/GIMT_Encode2(GICXXPred_MI_Predicate_GICombiner0),
+// CHECK-NEXT:      /* 466 */ GIM_CheckCxxInsnPredicate, /*MI*/0, /*FnId*/GIMT_Encode2(GICXXPred_MI_Predicate_GICombiner1),
+// CHECK-NEXT:      /* 470 */ // Combiner Rule #2: TwoMatchNoApply
+// CHECK-NEXT:      /* 470 */ GIR_EraseRootFromParent_Done,
+// CHECK-NEXT:      /* 471 */ // Label 6: @471
 // CHECK-NEXT:      /* 471 */ GIM_Reject,
-// CHECK-NEXT:      /* 472 */ // Label 2: @472
-// CHECK-NEXT:      /* 472 */ GIM_Try, /*On fail goto*//*Label 8*/ GIMT_Encode4(483), // Rule ID 4 //
-// CHECK-NEXT:      /* 477 */   GIM_CheckSimplePredicate, GIMT_Encode2(GICXXPred_Simple_IsRule4Enabled),
-// CHECK-NEXT:      /* 480 */   // MIs[0] a
-// CHECK-NEXT:      /* 480 */   // No operand predicates
-// CHECK-NEXT:      /* 480 */   // MIs[0] y
-// CHECK-NEXT:      /* 480 */   // No operand predicates
-// CHECK-NEXT:      /* 480 */   // Combiner Rule #4: CombineCXXOrder
-// CHECK-NEXT:      /* 480 */   GIR_DoneWithCustomAction, /*Fn*/GIMT_Encode2(GICXXCustomAction_GICombiner3),
-// CHECK-NEXT:      /* 483 */ // Label 8: @483
+// CHECK-NEXT:      /* 472 */ // Label 1: @472
+// CHECK-NEXT:      /* 472 */ GIM_Try, /*On fail goto*//*Label 7*/ GIMT_Encode4(483), // Rule ID 3 //
+// CHECK-NEXT:      /* 477 */ GIM_CheckSimplePredicate, GIMT_Encode2(GICXXPred_Simple_IsRule3Enabled),
+// CHECK-NEXT:      /* 480 */ // MIs[0] a
+// CHECK-NEXT:      /* 480 */ // No operand predicates
+// CHECK-NEXT:      /* 480 */ // MIs[0] y
+// CHECK-NEXT:      /* 480 */ // No operand predicates
+// CHECK-NEXT:      /* 480 */ // Combiner Rule #3: NoMatchTwoApply
+// CHECK-NEXT:      /* 480 */ GIR_DoneWithCustomAction, /*Fn*/GIMT_Encode2(GICXXCustomAction_GICombiner2),
+// CHECK-NEXT:      /* 483 */ // Label 7: @483
 // CHECK-NEXT:      /* 483 */ GIM_Reject,
-// CHECK-NEXT:      /* 484 */ // Label 3: @484
-// CHECK-NEXT:      /* 484 */ GIM_Try, /*On fail goto*//*Label 9*/ GIMT_Encode4(495), // Rule ID 1 //
-// CHECK-NEXT:      /* 489 */   GIM_CheckSimplePredicate, GIMT_Encode2(GICXXPred_Simple_IsRule1Enabled),
-// CHECK-NEXT:      /* 492 */   // MIs[0] a
-// CHECK-NEXT:      /* 492 */   // No operand predicates
-// CHECK-NEXT:      /* 492 */   // MIs[0] b
-// CHECK-NEXT:      /* 492 */   // No operand predicates
-// CHECK-NEXT:      /* 492 */   // Combiner Rule #1: TwoMatchTwoApply
-// CHECK-NEXT:      /* 492 */   GIR_DoneWithCustomAction, /*Fn*/GIMT_Encode2(GICXXCustomAction_GICombiner1),
-// CHECK-NEXT:      /* 495 */ // Label 9: @495
+// CHECK-NEXT:      /* 484 */ // Label 2: @484
+// CHECK-NEXT:      /* 484 */ GIM_Try, /*On fail goto*//*Label 8*/ GIMT_Encode4(495), // Rule ID 4 //
+// CHECK-NEXT:      /* 489 */ GIM_CheckSimplePredicate, GIMT_Encode2(GICXXPred_Simple_IsRule4Enabled),
+// CHECK-NEXT:      /* 492 */ // MIs[0] a
+// CHECK-NEXT:      /* 492 */ // No operand predicates
+// CHECK-NEXT:      /* 492 */ // MIs[0] y
+// CHECK-NEXT:      /* 492 */ // No operand predicates
+// CHECK-NEXT:      /* 492 */ // Combiner Rule #4: CombineCXXOrder
+// CHECK-NEXT:      /* 492 */ GIR_DoneWithCustomAction, /*Fn*/GIMT_Encode2(GICXXCustomAction_GICombiner3),
+// CHECK-NEXT:      /* 495 */ // Label 8: @495
 // CHECK-NEXT:      /* 495 */ GIM_Reject,
-// CHECK...
[truncated]

davemgreen · 2025-07-08T14:20:31Z

llvm/include/llvm/CodeGen/GlobalISel/MachineIRBuilder.h

+
+  /// Build and insert \p Res = \p G_TRUNC_USAT_U \p Op
+  ///
+  /// G_TRUNC_SSAT_S truncates the saturated unsigned input, \p Op, to a


G_TRUNC_USAT_U

davemgreen · 2025-07-08T14:20:45Z

llvm/include/llvm/CodeGen/GlobalISel/MachineIRBuilder.h

+  ///
+  /// G_TRUNC_SSAT_S truncates the saturated unsigned input, \p Op, to a
+  /// unsigned result.
+  ///  ///


Do these ///'s mean something that I haven't seen before?

I'm not actually too sure - I was basing this off of the layout of some comments within the file which I was referencing. I was unsure if this was a formatting thing, but other EXT and TRUNCs have similar comments

The leading ones are doxygen, the second one in from that I'm not sure

Yeah it was the second ones in that I wasn't sure of, it might have meant something special to the output doxygen. As they are not on all the other functions we could remove them and see if anyone complains. It looks like a mistaken formatting gone awry.

Makes sense - I'll remove the double ///s that appear then

davemgreen

LGTM, Thanks

jayfoad · 2025-07-09T12:44:15Z

llvm/docs/GlobalISel/GenericOpcode.rst

+G_TRUNC_SSAT_S
+^^^^^^^^^^^^^^
+
+Truncate a saturated signed input to a signed result.


I don't think it makes sense to describe the input as saturated. Rather the operation is "truncate with saturation". So I would suggest:

Suggested change

Truncate a saturated signed input to a signed result.

Truncate a signed input to a signed result with saturation.

or

Suggested change

Truncate a saturated signed input to a signed result.

Saturated truncation from a signed input to a signed result.

Same in lots of places below.

llvmbot added backend:AArch64 llvm:codegen mc Machine (object) code llvm:globalisel llvm:support labels Jul 8, 2025

jyli0116 requested a review from davemgreen July 8, 2025 14:59

arsenm approved these changes Jul 8, 2025

View reviewed changes

davemgreen reviewed Jul 8, 2025

View reviewed changes

davemgreen requested a review from aemerson July 8, 2025 15:14

davemgreen approved these changes Jul 8, 2025

View reviewed changes

jayfoad reviewed Jul 9, 2025

View reviewed changes

jyli0116 added 2 commits July 9, 2025 13:51

[GlobalISel] Add Saturated Truncate Instructions

81db890

incorrect comment changes

59a262d

jyli0116 force-pushed the GISel_trunc_sat branch from b182036 to 59a262d Compare July 9, 2025 14:11

jyli0116 added 2 commits July 9, 2025 14:31

change comment wording

2bd4234

edit comments

bdfceb1

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

[GlobalISel] Add Saturated Truncate Instructions #147526

[GlobalISel] Add Saturated Truncate Instructions #147526

jyli0116 commented Jul 8, 2025

Uh oh!

llvmbot commented Jul 8, 2025 •

edited

Loading

Uh oh!

llvmbot commented Jul 8, 2025

Uh oh!

davemgreen Jul 8, 2025

Uh oh!

davemgreen Jul 8, 2025

Uh oh!

jyli0116 Jul 8, 2025

Uh oh!

arsenm Jul 8, 2025

Uh oh!

davemgreen Jul 8, 2025

Uh oh!

jyli0116 Jul 8, 2025

Uh oh!

davemgreen left a comment

Uh oh!

jayfoad Jul 9, 2025

Uh oh!

Uh oh!

	Truncate a saturated signed input to a signed result.
	Truncate a signed input to a signed result with saturation.

	Truncate a saturated signed input to a signed result.
	Saturated truncation from a signed input to a signed result.

[GlobalISel] Add Saturated Truncate Instructions #147526

Are you sure you want to change the base?

[GlobalISel] Add Saturated Truncate Instructions #147526

Conversation

jyli0116 commented Jul 8, 2025

Uh oh!

llvmbot commented Jul 8, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

llvmbot commented Jul 8, 2025

Uh oh!

davemgreen Jul 8, 2025

Choose a reason for hiding this comment

Uh oh!

davemgreen Jul 8, 2025

Choose a reason for hiding this comment

Uh oh!

jyli0116 Jul 8, 2025

Choose a reason for hiding this comment

Uh oh!

arsenm Jul 8, 2025

Choose a reason for hiding this comment

Uh oh!

davemgreen Jul 8, 2025

Choose a reason for hiding this comment

Uh oh!

jyli0116 Jul 8, 2025

Choose a reason for hiding this comment

Uh oh!

davemgreen left a comment

Choose a reason for hiding this comment

Uh oh!

jayfoad Jul 9, 2025

Choose a reason for hiding this comment

Uh oh!

Uh oh!

llvmbot commented Jul 8, 2025 •

edited

Loading