https://github.com/AtariDreams created
https://github.com/llvm/llvm-project/pull/86967
None
>From 74c168b790f8daabf68426ce3fdffee0348f126b Mon Sep 17 00:00:00 2001
From: Rose <gfunni...@gmail.com>
Date: Thu, 28 Mar 2024 12:12:57 -0400
Subject: [PATCH] [CGBuiltin] Use freeze instruction to create an undef value
instead of zero
---
clang/lib/CodeGen/CGBuiltin.cpp | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index 5ab5917c0c8da7..179c0cf3cc905a 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -14305,11 +14305,9 @@ Value *CodeGenFunction::EmitX86BuiltinExpr(unsigned
BuiltinID,
case X86::BI__builtin_ia32_undef256:
case X86::BI__builtin_ia32_undef512:
// The x86 definition of "undef" is not the same as the LLVM definition
- // (PR32176). We leave optimizing away an unnecessary zero constant to the
- // IR optimizer and backend.
- // TODO: If we had a "freeze" IR instruction to generate a fixed undef
- // value, we should use that here instead of a zero.
- return llvm::Constant::getNullValue(ConvertType(E->getType()));
+ // (PR32176). Use a "freeze" IR instruction to generate a fixed undef
+ // value.
+ return Builder.CreateFreeze(UndefValue::get(ConvertType(E->getType())));
case X86::BI__builtin_ia32_vec_init_v8qi:
case X86::BI__builtin_ia32_vec_init_v4hi:
case X86::BI__builtin_ia32_vec_init_v2si:
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