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result is non-zero. Implement an example optimization (PR9814), which allows us to transform: A / ((1 << B) >>u 2) into: A >>u (B-2) which we compile into: _divu3: ## @divu3 leal -2(%rsi), %ecx shrl %cl, %edi movl %edi, %eax ret instead of: _divu3: ## @divu3 movb %sil, %cl movl $1, %esi shll %cl, %esi shrl $2, %esi movl %edi, %eax xorl %edx, %edx divl %esi, %eax ret git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131860 91177308-0d34-0410-b5e6-96231b3b80d8
135 lines
3.1 KiB
LLVM
135 lines
3.1 KiB
LLVM
; This test makes sure that div instructions are properly eliminated.
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; RUN: opt < %s -instcombine -S | FileCheck %s
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define i32 @test1(i32 %A) {
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%B = sdiv i32 %A, 1 ; <i32> [#uses=1]
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ret i32 %B
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; CHECK: @test1
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; CHECK-NEXT: ret i32 %A
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}
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define i32 @test2(i32 %A) {
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; => Shift
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%B = udiv i32 %A, 8 ; <i32> [#uses=1]
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ret i32 %B
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; CHECK: @test2
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; CHECK-NEXT: lshr i32 %A, 3
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}
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define i32 @test3(i32 %A) {
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; => 0, don't need to keep traps
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%B = sdiv i32 0, %A ; <i32> [#uses=1]
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ret i32 %B
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; CHECK: @test3
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; CHECK-NEXT: ret i32 0
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}
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define i32 @test4(i32 %A) {
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; 0-A
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%B = sdiv i32 %A, -1 ; <i32> [#uses=1]
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ret i32 %B
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; CHECK: @test4
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; CHECK-NEXT: sub i32 0, %A
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}
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define i32 @test5(i32 %A) {
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%B = udiv i32 %A, -16 ; <i32> [#uses=1]
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%C = udiv i32 %B, -4 ; <i32> [#uses=1]
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ret i32 %C
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; CHECK: @test5
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; CHECK-NEXT: ret i32 0
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}
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define i1 @test6(i32 %A) {
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%B = udiv i32 %A, 123 ; <i32> [#uses=1]
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; A < 123
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%C = icmp eq i32 %B, 0 ; <i1> [#uses=1]
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ret i1 %C
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; CHECK: @test6
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; CHECK-NEXT: icmp ult i32 %A, 123
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}
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define i1 @test7(i32 %A) {
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%B = udiv i32 %A, 10 ; <i32> [#uses=1]
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; A >= 20 && A < 30
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%C = icmp eq i32 %B, 2 ; <i1> [#uses=1]
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ret i1 %C
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; CHECK: @test7
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; CHECK-NEXT: add i32 %A, -20
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; CHECK-NEXT: icmp ult i32
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}
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define i1 @test8(i8 %A) {
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%B = udiv i8 %A, 123 ; <i8> [#uses=1]
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; A >= 246
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%C = icmp eq i8 %B, 2 ; <i1> [#uses=1]
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ret i1 %C
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; CHECK: @test8
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; CHECK-NEXT: icmp ugt i8 %A, -11
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}
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define i1 @test9(i8 %A) {
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%B = udiv i8 %A, 123 ; <i8> [#uses=1]
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; A < 246
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%C = icmp ne i8 %B, 2 ; <i1> [#uses=1]
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ret i1 %C
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; CHECK: @test9
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; CHECK-NEXT: icmp ult i8 %A, -10
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}
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define i32 @test10(i32 %X, i1 %C) {
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%V = select i1 %C, i32 64, i32 8 ; <i32> [#uses=1]
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%R = udiv i32 %X, %V ; <i32> [#uses=1]
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ret i32 %R
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; CHECK: @test10
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; CHECK-NEXT: select i1 %C, i32 6, i32 3
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; CHECK-NEXT: lshr i32 %X
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}
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define i32 @test11(i32 %X, i1 %C) {
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%A = select i1 %C, i32 1024, i32 32 ; <i32> [#uses=1]
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%B = udiv i32 %X, %A ; <i32> [#uses=1]
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ret i32 %B
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; CHECK: @test11
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; CHECK-NEXT: select i1 %C, i32 10, i32 5
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; CHECK-NEXT: lshr i32 %X
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}
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; PR2328
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define i32 @test12(i32 %x) nounwind {
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%tmp3 = udiv i32 %x, %x ; 1
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ret i32 %tmp3
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; CHECK: @test12
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; CHECK-NEXT: ret i32 1
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}
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define i32 @test13(i32 %x) nounwind {
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%tmp3 = sdiv i32 %x, %x ; 1
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ret i32 %tmp3
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; CHECK: @test13
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; CHECK-NEXT: ret i32 1
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}
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define i32 @test14(i8 %x) nounwind {
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%zext = zext i8 %x to i32
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%div = udiv i32 %zext, 257 ; 0
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ret i32 %div
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; CHECK: @test14
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; CHECK-NEXT: ret i32 0
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}
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; PR9814
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define i32 @test15(i32 %a, i32 %b) nounwind {
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%shl = shl i32 1, %b
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%div = lshr i32 %shl, 2
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%div2 = udiv i32 %a, %div
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ret i32 %div2
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; CHECK: @test15
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; CHECK-NEXT: add i32 %b, -2
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; CHECK-NEXT: lshr i32 %a,
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; CHECK-NEXT: ret i32
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}
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