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e3d920699c
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
12 lines
275 B
LLVM
12 lines
275 B
LLVM
; RUN: llvm-as < %s | llc -march=x86-64 | grep mov | count 1
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; Do eliminate the zero-extension instruction and rely on
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; x86-64's implicit zero-extension!
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define i64 @foo(i32* %p) nounwind {
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%t = load i32* %p
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%n = add i32 %t, 1
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%z = zext i32 %n to i64
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ret i64 %z
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}
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