From 9ee7123ab462d97a2b242280e9bf0b47883531cb Mon Sep 17 00:00:00 2001 From: Dan Gohman Date: Wed, 17 Feb 2010 00:54:58 +0000 Subject: [PATCH] Fold bswap(undef) to undef. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@96432 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Analysis/ConstantFolding.cpp | 6 ++++++ test/Transforms/InstCombine/bswap-fold.ll | 6 ++++++ 2 files changed, 12 insertions(+) diff --git a/lib/Analysis/ConstantFolding.cpp b/lib/Analysis/ConstantFolding.cpp index 6bab5eca200..676a8466ac2 100644 --- a/lib/Analysis/ConstantFolding.cpp +++ b/lib/Analysis/ConstantFolding.cpp @@ -1179,6 +1179,12 @@ llvm::ConstantFoldCall(Function *F, return 0; } + if (isa(Operands[0])) { + if (Name.startswith("llvm.bswap")) + return Operands[0]; + return 0; + } + return 0; } diff --git a/test/Transforms/InstCombine/bswap-fold.ll b/test/Transforms/InstCombine/bswap-fold.ll index 034c70e400c..a6b30c053eb 100644 --- a/test/Transforms/InstCombine/bswap-fold.ll +++ b/test/Transforms/InstCombine/bswap-fold.ll @@ -67,3 +67,9 @@ define i16 @test8(i64 %A) { %D = tail call i16 @llvm.bswap.i16(i16 %C) nounwind ret i16 %D } + +; Misc: Fold bswap(undef) to undef. +define i64 @foo() { + %a = call i64 @llvm.bswap.i64(i64 undef) + ret i64 %a +} -- 2.34.1