[GlobalIsel] add trunc flags (#87045)

#85592

Author: Thorsten Schütt

llvm/lib/CodeGen/MachineInstr.cpp

@@ -39,6 +39,7 @@
 #include "llvm/IR/DebugLoc.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/InlineAsm.h"
+#include "llvm/IR/Instructions.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Metadata.h"
 #include "llvm/IR/Module.h"
@@ -553,6 +554,11 @@ uint32_t MachineInstr::copyFlagsFromInstruction(const Instruction &I) {
       MIFlags |= MachineInstr::MIFlag::NoSWrap;
     if (OB->hasNoUnsignedWrap())
       MIFlags |= MachineInstr::MIFlag::NoUWrap;
+  } else if (const TruncInst *TI = dyn_cast<TruncInst>(&I)) {
+    if (TI->hasNoSignedWrap())
+      MIFlags |= MachineInstr::MIFlag::NoSWrap;
+    if (TI->hasNoUnsignedWrap())
+      MIFlags |= MachineInstr::MIFlag::NoUWrap;
   }
 
   // Copy the nonneg flag.

llvm/test/CodeGen/AArch64/GlobalISel/irtranslator-trunc.ll

@@ -0,0 +1,90 @@
+; NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+; RUN: llc -O0 -mtriple=aarch64-linux-gnu -global-isel -stop-after=irtranslator %s -o - | FileCheck %s
+
+define i32 @call_trunc_no_flags(i64 %a) {
+  ; CHECK-LABEL: name: call_trunc_no_flags
+  ; CHECK: bb.1.entry:
+  ; CHECK-NEXT:   liveins: $x0
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   [[COPY:%[0-9]+]]:_(s64) = COPY $x0
+  ; CHECK-NEXT:   [[TRUNC:%[0-9]+]]:_(s32) = G_TRUNC [[COPY]](s64)
+  ; CHECK-NEXT:   $w0 = COPY [[TRUNC]](s32)
+  ; CHECK-NEXT:   RET_ReallyLR implicit $w0
+entry:
+  %result = trunc i64 %a to i32
+  ret i32 %result
+}
+
+define i32 @call_trunc_nsw_flags(i64 %a) {
+  ; CHECK-LABEL: name: call_trunc_nsw_flags
+  ; CHECK: bb.1.entry:
+  ; CHECK-NEXT:   liveins: $x0
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   [[COPY:%[0-9]+]]:_(s64) = COPY $x0
+  ; CHECK-NEXT:   [[TRUNC:%[0-9]+]]:_(s32) = nsw G_TRUNC [[COPY]](s64)
+  ; CHECK-NEXT:   $w0 = COPY [[TRUNC]](s32)
+  ; CHECK-NEXT:   RET_ReallyLR implicit $w0
+entry:
+  %result = trunc nsw i64 %a to i32
+  ret i32 %result
+}
+
+define i32 @call_trunc_nuw_flags(i64 %a) {
+  ; CHECK-LABEL: name: call_trunc_nuw_flags
+  ; CHECK: bb.1.entry:
+  ; CHECK-NEXT:   liveins: $x0
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   [[COPY:%[0-9]+]]:_(s64) = COPY $x0
+  ; CHECK-NEXT:   [[TRUNC:%[0-9]+]]:_(s32) = nuw G_TRUNC [[COPY]](s64)
+  ; CHECK-NEXT:   $w0 = COPY [[TRUNC]](s32)
+  ; CHECK-NEXT:   RET_ReallyLR implicit $w0
+entry:
+  %result = trunc nuw i64 %a to i32
+  ret i32 %result
+}
+
+define i32 @call_trunc_all_flags(i64 %a) {
+  ; CHECK-LABEL: name: call_trunc_all_flags
+  ; CHECK: bb.1.entry:
+  ; CHECK-NEXT:   liveins: $x0
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   [[COPY:%[0-9]+]]:_(s64) = COPY $x0
+  ; CHECK-NEXT:   [[TRUNC:%[0-9]+]]:_(s32) = nuw nsw G_TRUNC [[COPY]](s64)
+  ; CHECK-NEXT:   $w0 = COPY [[TRUNC]](s32)
+  ; CHECK-NEXT:   RET_ReallyLR implicit $w0
+entry:
+  %result = trunc nsw nuw i64 %a to i32
+  ret i32 %result
+}
+
+define <2 x i64> @call_trunc_noop_signed_vector(<2 x i64> %a) {
+  ; CHECK-LABEL: name: call_trunc_noop_signed_vector
+  ; CHECK: bb.1.entry:
+  ; CHECK-NEXT:   liveins: $q0
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   [[COPY:%[0-9]+]]:_(<2 x s64>) = COPY $q0
+  ; CHECK-NEXT:   [[TRUNC:%[0-9]+]]:_(<2 x s32>) = nsw G_TRUNC [[COPY]](<2 x s64>)
+  ; CHECK-NEXT:   [[SEXT:%[0-9]+]]:_(<2 x s64>) = G_SEXT [[TRUNC]](<2 x s32>)
+  ; CHECK-NEXT:   $q0 = COPY [[SEXT]](<2 x s64>)
+  ; CHECK-NEXT:   RET_ReallyLR implicit $q0
+entry:
+  %truncate = trunc nsw <2 x i64> %a to <2 x i32>
+  %result = sext <2 x i32> %truncate to <2 x i64>
+  ret <2 x i64> %result
+}
+
+define <2 x i64> @call_trunc_noop_unsigned_vector(<2 x i64> %a) {
+  ; CHECK-LABEL: name: call_trunc_noop_unsigned_vector
+  ; CHECK: bb.1.entry:
+  ; CHECK-NEXT:   liveins: $q0
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   [[COPY:%[0-9]+]]:_(<2 x s64>) = COPY $q0
+  ; CHECK-NEXT:   [[TRUNC:%[0-9]+]]:_(<2 x s32>) = nuw G_TRUNC [[COPY]](<2 x s64>)
+  ; CHECK-NEXT:   [[ZEXT:%[0-9]+]]:_(<2 x s64>) = G_ZEXT [[TRUNC]](<2 x s32>)
+  ; CHECK-NEXT:   $q0 = COPY [[ZEXT]](<2 x s64>)
+  ; CHECK-NEXT:   RET_ReallyLR implicit $q0
+entry:
+  %truncate = trunc nuw <2 x i64> %a to <2 x i32>
+  %result = zext <2 x i32> %truncate to <2 x i64>
+  ret <2 x i64> %result
+}