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| author | Dan Gohman <gohman@apple.com> | 2008-08-07 02:54:50 +0000 |
|---|---|---|
| committer | Dan Gohman <gohman@apple.com> | 2008-08-07 02:54:50 +0000 |
| commit | e3d920699c6df959f3e0844aeadd983b2955b23e (patch) | |
| tree | 7578dc6bd96037d61f965d03bac25fbe96259ad7 /test/CodeGen/X86/subreg-to-reg-0.ll | |
| parent | 865db4566e84b788e5738fec462804a779223b8b (diff) | |
| download | llvm-e3d920699c6df959f3e0844aeadd983b2955b23e.tar.gz llvm-e3d920699c6df959f3e0844aeadd983b2955b23e.tar.bz2 llvm-e3d920699c6df959f3e0844aeadd983b2955b23e.tar.xz | |
Re-enable elimination of unnecessary SUBREG_TO_REG instructions in
LowerSubregs, and fix an x86-64 isel bug that this exposed.
SUBREG_TO_REG for x86-64 implicit zero extension is only safe for
isel to generate when the source is known to always have zeros in
the high 32 bits. The EXTRACT_SUBREG instruction does not clear
the high 32 bits.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@54444 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'test/CodeGen/X86/subreg-to-reg-0.ll')
| -rw-r--r-- | test/CodeGen/X86/subreg-to-reg-0.ll | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/test/CodeGen/X86/subreg-to-reg-0.ll b/test/CodeGen/X86/subreg-to-reg-0.ll new file mode 100644 index 0000000000..6b60f65265 --- /dev/null +++ b/test/CodeGen/X86/subreg-to-reg-0.ll @@ -0,0 +1,11 @@ +; RUN: llvm-as < %s | llc -march=x86-64 | grep mov | count 1 + +; Do eliminate the zero-extension instruction and rely on +; x86-64's implicit zero-extension! + +define i64 @foo(i32* %p) nounwind { + %t = load i32* %p + %n = add i32 %t, 1 + %z = zext i32 %n to i64 + ret i64 %z +} |