[CodeGen] Parse nusw flag (#138856)

Fixes #127781

Author: Pierre-vh

llvm/lib/CodeGen/MIRParser/MIParser.cpp

@@ -1476,6 +1476,7 @@ bool MIParser::parseInstruction(unsigned &OpCode, unsigned &Flags) {
          Token.is(MIToken::kw_unpredictable) ||
          Token.is(MIToken::kw_nneg) ||
          Token.is(MIToken::kw_disjoint) ||
+         Token.is(MIToken::kw_nusw) ||
          Token.is(MIToken::kw_samesign)) {
     // clang-format on
     // Mine frame and fast math flags
@@ -1513,6 +1514,8 @@ bool MIParser::parseInstruction(unsigned &OpCode, unsigned &Flags) {
       Flags |= MachineInstr::NonNeg;
     if (Token.is(MIToken::kw_disjoint))
       Flags |= MachineInstr::Disjoint;
+    if (Token.is(MIToken::kw_nusw))
+      Flags |= MachineInstr::NoUSWrap;
     if (Token.is(MIToken::kw_samesign))
       Flags |= MachineInstr::SameSign;
 

llvm/test/CodeGen/MIR/AMDGPU/ptradd-flags.mir

@@ -0,0 +1,23 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 5
+# RUN: llc -mtriple=amdgcn -mcpu=gfx900 -run-pass=none  %s -o - | FileCheck %s
+
+---
+name:  nusw_ptr_add
+legalized:       true
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $vgpr0_vgpr1, $vgpr2_vgpr3
+
+    ; CHECK-LABEL: name: nusw_ptr_add
+    ; CHECK: liveins: $vgpr0_vgpr1, $vgpr2_vgpr3
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: %ptr:_(p0) = COPY $vgpr0_vgpr1
+    ; CHECK-NEXT: %off:_(s64) = COPY $vgpr2_vgpr3
+    ; CHECK-NEXT: %ret:_(p0) = nuw nusw G_PTR_ADD %ptr, %off(s64)
+    ; CHECK-NEXT: $vgpr0_vgpr1 = COPY %ret(p0)
+    %ptr:_(p0) = COPY $vgpr0_vgpr1
+    %off:_(s64) = COPY $vgpr2_vgpr3
+    %ret:_(p0) = nuw nusw G_PTR_ADD %ptr, %off
+    $vgpr0_vgpr1 = COPY %ret
+...