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https://github.com/RPCS3/llvm-mirror.git
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6e799c3c58
int tries = INT_MAX;
while (tries > 0) {
tries--;
}
The check should be:
subs r4, #1
cmp r4, #0
bgt LBB0_1
The subs can set the overflow V bit when r4 is INT_MAX+1 (which loop
canonicalization apparently does in this case). cmp #0 would have cleared
it while not changing the N and Z bits. Since BGT is dependent on the V
bit, i.e. (N == V) && !Z, it is not safe to eliminate the cmp #0.
rdar://9172742
llvm-svn: 128179
48 lines
1.0 KiB
LLVM
48 lines
1.0 KiB
LLVM
; RUN: llc < %s -march=arm | FileCheck %s
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define i64 @f0(i64 %A, i64 %B) {
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; CHECK: f0
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; CHECK: lsrs r3, r3, #1
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; CHECK-NEXT: rrx r2, r2
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; CHECK-NEXT: subs r0, r0, r2
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; CHECK-NEXT: sbc r1, r1, r3
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%tmp = bitcast i64 %A to i64
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%tmp2 = lshr i64 %B, 1
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%tmp3 = sub i64 %tmp, %tmp2
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ret i64 %tmp3
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}
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define i32 @f1(i64 %x, i64 %y) {
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; CHECK: f1
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; CHECK: lsl{{.*}}r2
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%a = shl i64 %x, %y
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%b = trunc i64 %a to i32
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ret i32 %b
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}
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define i32 @f2(i64 %x, i64 %y) {
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; CHECK: f2
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; CHECK: lsr{{.*}}r2
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; CHECK-NEXT: rsb r3, r2, #32
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; CHECK-NEXT: sub r2, r2, #32
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; CHECK-NEXT: cmp r2, #0
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; CHECK-NEXT: orr r0, r0, r1, lsl r3
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; CHECK-NEXT: asrge r0, r1, r2
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%a = ashr i64 %x, %y
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%b = trunc i64 %a to i32
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ret i32 %b
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}
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define i32 @f3(i64 %x, i64 %y) {
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; CHECK: f3
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; CHECK: lsr{{.*}}r2
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; CHECK-NEXT: rsb r3, r2, #32
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; CHECK-NEXT: sub r2, r2, #32
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; CHECK-NEXT: cmp r2, #0
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; CHECK-NEXT: orr r0, r0, r1, lsl r3
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; CHECK-NEXT: lsrge r0, r1, r2
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%a = lshr i64 %x, %y
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%b = trunc i64 %a to i32
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ret i32 %b
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}
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