llvm-6502/test/CodeGen/X86/zext-shl.ll
Evan Cheng 9818c043d2 Make 91378 more conservative.
1. Only perform (zext (shl (zext x), y)) -> (shl (zext x), y) when y is a constant. This makes sure it remove at least one zest.
2. If the shift is a left shift, make sure the original shift cannot shift out bits.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91399 91177308-0d34-0410-b5e6-96231b3b80d8
2009-12-15 03:00:32 +00:00

26 lines
461 B
LLVM

; RUN: llc < %s -march=x86 | FileCheck %s
define i32 @t1(i8 zeroext %x) nounwind readnone ssp {
entry:
; CHECK: t1:
; CHECK: shll
; CHECK-NOT: movzwl
; CHECK: ret
%0 = zext i8 %x to i16
%1 = shl i16 %0, 5
%2 = zext i16 %1 to i32
ret i32 %2
}
define i32 @t2(i8 zeroext %x) nounwind readnone ssp {
entry:
; CHECK: t2:
; CHECK: shrl
; CHECK-NOT: movzwl
; CHECK: ret
%0 = zext i8 %x to i16
%1 = lshr i16 %0, 3
%2 = zext i16 %1 to i32
ret i32 %2
}