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| author | Dan Gohman <dan433584@gmail.com> | 2013-01-31 23:49:33 +0000 |
|---|---|---|
| committer | Dan Gohman <dan433584@gmail.com> | 2013-01-31 23:49:33 +0000 |
| commit | ac08785edaac826afe11a4e596a46fc693848848 (patch) | |
| tree | 3113dd8303ade3bda241d64bc22e2ced5e711207 /test/Transforms/InstSimplify | |
| parent | 27aacedf7d975243170206efb948a20d6fd4a2c1 (diff) | |
| download | external_llvm-ac08785edaac826afe11a4e596a46fc693848848.zip external_llvm-ac08785edaac826afe11a4e596a46fc693848848.tar.gz external_llvm-ac08785edaac826afe11a4e596a46fc693848848.tar.bz2 | |
An alloca can be equal to an argument. It can't *alias* an alloca, but it could
be equal, since there's nothing preventing a caller from correctly predicting
the stack location of an alloca.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174119 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'test/Transforms/InstSimplify')
| -rw-r--r-- | test/Transforms/InstSimplify/compare.ll | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/test/Transforms/InstSimplify/compare.ll b/test/Transforms/InstSimplify/compare.ll index 56627b9..a6d7a64 100644 --- a/test/Transforms/InstSimplify/compare.ll +++ b/test/Transforms/InstSimplify/compare.ll @@ -647,3 +647,16 @@ unreachableblock: %Y = icmp eq i32* %X, null ret i1 %Y } + +; It's not valid to fold a comparison of an argument with an alloca, even though +; that's tempting. An argument can't *alias* an alloca, however the aliasing rule +; relies on restrictions against guessing an object's address and dereferencing. +; There are no restrictions against guessing an object's address and comparing. + +define i1 @alloca_argument_compare(i64* %arg) { + %alloc = alloca i64 + %cmp = icmp eq i64* %arg, %alloc + ret i1 %cmp + ; CHECK: alloca_argument_compare + ; CHECK: ret i1 %cmp +} |