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llvm-mirror/test/CodeGen/X86/pr28504.ll
Michael Kuperstein ad3a898d94 [DAGCombine] Make sext(setcc) combine respect getBooleanContents
We used to combine "sext(setcc x, y, cc) -> (select (setcc x, y, cc), -1, 0)"
Instead, we should combine to (select (setcc x, y, cc), T, 0) where the value
of T is 1 or -1, depending on the type of the setcc, and getBooleanContents()
for the type if it is not i1.

This fixes PR28504.

llvm-svn: 277371
2016-08-01 19:39:49 +00:00

38 lines
1.3 KiB
LLVM

; RUN: llc -mtriple=x86_64-unknown-linux-gnu < %s | FileCheck %s
; The test case is rather involved, because we need to get to a state where
; We have a sext(setcc x, y, cc) -> (select (setcc x, y, cc), T, 0) combine,
; BUT this combine is only triggered post-legalization, so the setcc's return
; type is i8. So we can't have the combine opportunity be exposed too early.
; Basically, what we want to see is that the compare result zero-extended, and
; then stored. Only one zext, and no sexts.
; CHECK-LABEL: main:
; CHECK: movzbl (%rdi), %[[EAX:.*]]
; CHECK-NEXT: xorl %e[[C:.]]x, %e[[C]]x
; CHECK-NEXT: cmpl $1, %[[EAX]]
; CHECK-NEXT: sete %[[C]]l
; CHECK-NEXT: movl %e[[C]]x, (%rsi)
define void @main(i8* %p, i32* %q) {
bb:
%tmp4 = load i8, i8* %p, align 1
%tmp5 = sext i8 %tmp4 to i32
%tmp6 = load i8, i8* %p, align 1
%tmp7 = zext i8 %tmp6 to i32
%tmp8 = sub nsw i32 %tmp5, %tmp7
%tmp11 = icmp eq i32 %tmp7, 1
%tmp12 = zext i1 %tmp11 to i32
%tmp13 = add nsw i32 %tmp8, %tmp12
%tmp14 = trunc i32 %tmp13 to i8
%tmp15 = sext i8 %tmp14 to i16
%tmp16 = sext i16 %tmp15 to i32
store i32 %tmp16, i32* %q, align 4
br i1 %tmp11, label %bb21, label %bb22
bb21: ; preds = %bb
unreachable
bb22: ; preds = %bb
ret void
}