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https://github.com/c64scene-ar/llvm-6502.git
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f922d9cfe4
This case is interesting because ScalarEvolutionExpander lowers min(a, b) as ~max(~a,~b). I think the profitability heuristics can be made more clever/aggressive, but this is a start. Differential Revision: http://reviews.llvm.org/D7821 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230285 91177308-0d34-0410-b5e6-96231b3b80d8
69 lines
1.9 KiB
LLVM
69 lines
1.9 KiB
LLVM
; RUN: opt -S -instcombine < %s | FileCheck %s
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define i32 @compute_min_2(i32 %x, i32 %y) {
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; CHECK-LABEL: compute_min_2
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entry:
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%not_x = sub i32 -1, %x
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%not_y = sub i32 -1, %y
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%cmp = icmp sgt i32 %not_x, %not_y
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%not_min = select i1 %cmp, i32 %not_x, i32 %not_y
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%min = sub i32 -1, %not_min
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ret i32 %min
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; CHECK: %0 = icmp slt i32 %x, %y
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; CHECK-NEXT: %1 = select i1 %0, i32 %x, i32 %y
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; CHECK-NEXT: ret i32 %1
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}
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define i32 @compute_min_3(i32 %x, i32 %y, i32 %z) {
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; CHECK-LABEL: compute_min_3
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entry:
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%not_x = sub i32 -1, %x
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%not_y = sub i32 -1, %y
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%not_z = sub i32 -1, %z
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%cmp_1 = icmp sgt i32 %not_x, %not_y
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%not_min_1 = select i1 %cmp_1, i32 %not_x, i32 %not_y
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%cmp_2 = icmp sgt i32 %not_min_1, %not_z
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%not_min_2 = select i1 %cmp_2, i32 %not_min_1, i32 %not_z
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%min = sub i32 -1, %not_min_2
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ret i32 %min
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; CHECK: %0 = icmp slt i32 %x, %y
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; CHECK-NEXT: %1 = select i1 %0, i32 %x, i32 %y
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; CHECK-NEXT: %2 = icmp slt i32 %1, %z
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; CHECK-NEXT: %3 = select i1 %2, i32 %1, i32 %z
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; CHECK-NEXT: ret i32 %3
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}
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define i32 @compute_min_arithmetic(i32 %x, i32 %y) {
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; CHECK-LABEL: compute_min_arithmetic
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entry:
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%not_value = sub i32 3, %x
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%not_y = sub i32 -1, %y
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%cmp = icmp sgt i32 %not_value, %not_y
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%not_min = select i1 %cmp, i32 %not_value, i32 %not_y
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ret i32 %not_min
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; CHECK: %0 = add i32 %x, -4
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; CHECK-NEXT: %1 = icmp slt i32 %0, %y
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; CHECK-NEXT: %2 = select i1 %1, i32 %0, i32 %y
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; CHECK-NEXT: %3 = xor i32 %2, -1
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; CHECK-NEXT: ret i32 %3
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}
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declare void @fake_use(i32)
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define i32 @compute_min_pessimization(i32 %x, i32 %y) {
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; CHECK-LABEL: compute_min_pessimization
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entry:
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%not_value = sub i32 3, %x
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call void @fake_use(i32 %not_value)
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%not_y = sub i32 -1, %y
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%cmp = icmp sgt i32 %not_value, %not_y
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; CHECK: %not_value = sub i32 3, %x
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; CHECK: %cmp = icmp sgt i32 %not_value, %not_y
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%not_min = select i1 %cmp, i32 %not_value, i32 %not_y
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%min = sub i32 -1, %not_min
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ret i32 %min
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}
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