shl_undef.ll
1.59 KB
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; RUN: llc < %s -O1 -mtriple=i386-apple-darwin -x86-asm-syntax=intel | FileCheck %s
;
; Interesting test case where %tmp1220 = xor i32 %tmp862, %tmp592 and
; %tmp1676 = xor i32 %tmp1634, %tmp1530 have zero demanded bits after
; DAGCombiner optimization pass. These are changed to undef and in turn
; the successor shl(s) become shl undef, 1. This pattern then matches
; shl x, 1 -> add x, x. add undef, undef doesn't guarantee the low
; order bit is zero and is incorrect.
;
; See rdar://9453156 and rdar://9487392.
;
; Use intel syntax, or "shl" might hit "pushl".
; CHECK-NOT: shl
define i32 @foo(i8* %a0, i32* %a2) nounwind {
entry:
%tmp0 = alloca i8
%tmp1 = alloca i32
store i8 1, i8* %tmp0
%tmp921.i7845 = load i8, i8* %a0, align 1
%tmp309 = xor i8 %tmp921.i7845, 104
%tmp592 = zext i8 %tmp309 to i32
%tmp862 = xor i32 1293461297, %tmp592
%tmp1220 = xor i32 %tmp862, %tmp592
%tmp1506 = shl i32 %tmp1220, 1
%tmp1530 = sub i32 %tmp592, %tmp1506
%tmp1557 = sub i32 %tmp1530, 542767629
%tmp1607 = and i32 %tmp1557, 1
store i32 %tmp1607, i32* %tmp1
%tmp1634 = and i32 %tmp1607, 2080309246
%tmp1676 = xor i32 %tmp1634, %tmp1530
%tmp1618 = shl i32 %tmp1676, 1
%tmp1645 = sub i32 %tmp862, %tmp1618
%tmp1697 = and i32 %tmp1645, 1
store i32 %tmp1697, i32* %a2
ret i32 %tmp1607
}
; CHECK-NOT: shl
; shl undef, 0 -> undef
define i32 @foo2_undef() nounwind {
entry:
%tmp2 = shl i32 undef, 0;
ret i32 %tmp2
}
; CHECK-NOT: shl
; shl undef, x -> 0
define i32 @foo1_undef(i32* %a0) nounwind {
entry:
%tmp1 = load i32, i32* %a0, align 1
%tmp2 = shl i32 undef, %tmp1;
ret i32 %tmp2
}