[X86] isGuaranteedNotToBeUndefOrPoisonForTargetNode - X86ISD::GlobalBaseReg and X86ISD::Wrapper/WrapperRIP nodes are never poison

[RKSimon]

Fixes #149841

[llvmbot]

@llvm/pr-subscribers-backend-x86

Author: Simon Pilgrim (RKSimon)

Changes

Fixes #149841

---

Full diff: https://github.com/llvm/llvm-project/pull/149854.diff

2 Files Affected:

• (modified) llvm/lib/Target/X86/X86ISelLowering.cpp (+4)
• (added) llvm/test/CodeGen/X86/pr149841.ll (+34)

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 62811244dcfee..858acc3c67de6 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -45059,6 +45059,10 @@ bool X86TargetLowering::isGuaranteedNotToBeUndefOrPoisonForTargetNode(
   unsigned NumElts = DemandedElts.getBitWidth();
 
   switch (Op.getOpcode()) {
+  case X86ISD::GlobalBaseReg:
+  case X86ISD::Wrapper:
+  case X86ISD::WrapperRIP:
+    return true;
   case X86ISD::BLENDI:
   case X86ISD::PSHUFD:
   case X86ISD::UNPCKL:
diff --git a/llvm/test/CodeGen/X86/pr149841.ll b/llvm/test/CodeGen/X86/pr149841.ll
new file mode 100644
index 0000000000000..c17a6172dee0c
--- /dev/null
+++ b/llvm/test/CodeGen/X86/pr149841.ll
@@ -0,0 +1,34 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
+; RUN: llc < %s | FileCheck %s
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+%struct.bar = type { [5 x ptr] }
+
+@global = external dso_local global %struct.bar
+
+define i1 @foo(ptr %arg, i1 %arg1) {
+; CHECK-LABEL: foo:
+; CHECK:       # %bb.0: # %bb
+; CHECK-NEXT:    cmpq $global+1, %rdi
+; CHECK-NEXT:    setne %al
+; CHECK-NEXT:    andb %sil, %al
+; CHECK-NEXT:    retq
+bb:
+  #dbg_value(ptr @global, !3, !DIExpression(), !5)
+  %icmp = icmp ne ptr %arg, getelementptr inbounds nuw (i8, ptr @global, i64 1)
+  %select = select i1 %arg1, i1 %icmp, i1 false
+  ret i1 %select
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!2}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C11, file: !1, isOptimized: false, runtimeVersion: 0, emissionKind: NoDebug)
+!1 = !DIFile(filename: "x.c", directory: "/proc/self/cwd")
+!2 = !{i32 2, !"Debug Info Version", i32 3}
+!3 = !DILocalVariable(name: "x", arg: 1, scope: !4, file: !1)
+!4 = distinct !DISubprogram(name: "x", scope: null, file: !1, spFlags: DISPFlagDefinition, unit: !0)
+!5 = !DILocation(line: 0, scope: !4)
+

[rupprecht]

Verified this fixes things, thanks!

[phoebewang]

Is it correct? In ValueTracking.cpp, we can only guarantee constant and strip cast GlobalVariable not to be undef or poison.