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https://github.com/c64scene-ar/llvm-6502.git
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f16d6b1ff1
EarlyCSE uses a simple generation scheme for handling memory-based dependencies, and calls to @llvm.assume (which are marked as writing to memory to ensure the preservation of control dependencies) disturb that scheme unnecessarily. Skipping calls to @llvm.assume is legal, and the alternative (adding AA calls in EarlyCSE) is likely undesirable (we have GVN for that). Fixes PR21448. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221175 91177308-0d34-0410-b5e6-96231b3b80d8
158 lines
3.3 KiB
LLVM
158 lines
3.3 KiB
LLVM
; RUN: opt < %s -S -early-cse | FileCheck %s
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declare void @llvm.assume(i1) nounwind
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; CHECK-LABEL: @test1(
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define void @test1(i8 %V, i32 *%P) {
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%A = bitcast i64 42 to double ;; dead
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%B = add i32 4, 19 ;; constant folds
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store i32 %B, i32* %P
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; CHECK-NEXT: store i32 23, i32* %P
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%C = zext i8 %V to i32
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%D = zext i8 %V to i32 ;; CSE
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store volatile i32 %C, i32* %P
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store volatile i32 %D, i32* %P
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; CHECK-NEXT: %C = zext i8 %V to i32
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; CHECK-NEXT: store volatile i32 %C
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; CHECK-NEXT: store volatile i32 %C
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%E = add i32 %C, %C
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%F = add i32 %C, %C
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store volatile i32 %E, i32* %P
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store volatile i32 %F, i32* %P
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; CHECK-NEXT: %E = add i32 %C, %C
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; CHECK-NEXT: store volatile i32 %E
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; CHECK-NEXT: store volatile i32 %E
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%G = add nuw i32 %C, %C ;; not a CSE with E
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store volatile i32 %G, i32* %P
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; CHECK-NEXT: %G = add nuw i32 %C, %C
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; CHECK-NEXT: store volatile i32 %G
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ret void
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}
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;; Simple load value numbering.
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; CHECK-LABEL: @test2(
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define i32 @test2(i32 *%P) {
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%V1 = load i32* %P
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%V2 = load i32* %P
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%Diff = sub i32 %V1, %V2
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ret i32 %Diff
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; CHECK: ret i32 0
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}
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; CHECK-LABEL: @test2a(
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define i32 @test2a(i32 *%P, i1 %b) {
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%V1 = load i32* %P
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tail call void @llvm.assume(i1 %b)
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%V2 = load i32* %P
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%Diff = sub i32 %V1, %V2
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ret i32 %Diff
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; CHECK: ret i32 0
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}
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;; Cross block load value numbering.
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; CHECK-LABEL: @test3(
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define i32 @test3(i32 *%P, i1 %Cond) {
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%V1 = load i32* %P
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br i1 %Cond, label %T, label %F
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T:
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store i32 4, i32* %P
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ret i32 42
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F:
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%V2 = load i32* %P
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%Diff = sub i32 %V1, %V2
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ret i32 %Diff
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; CHECK: F:
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; CHECK: ret i32 0
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}
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; CHECK-LABEL: @test3a(
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define i32 @test3a(i32 *%P, i1 %Cond, i1 %b) {
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%V1 = load i32* %P
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br i1 %Cond, label %T, label %F
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T:
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store i32 4, i32* %P
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ret i32 42
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F:
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tail call void @llvm.assume(i1 %b)
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%V2 = load i32* %P
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%Diff = sub i32 %V1, %V2
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ret i32 %Diff
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; CHECK: F:
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; CHECK: ret i32 0
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}
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;; Cross block load value numbering stops when stores happen.
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; CHECK-LABEL: @test4(
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define i32 @test4(i32 *%P, i1 %Cond) {
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%V1 = load i32* %P
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br i1 %Cond, label %T, label %F
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T:
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ret i32 42
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F:
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; Clobbers V1
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store i32 42, i32* %P
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%V2 = load i32* %P
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%Diff = sub i32 %V1, %V2
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ret i32 %Diff
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; CHECK: F:
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; CHECK: ret i32 %Diff
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}
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declare i32 @func(i32 *%P) readonly
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;; Simple call CSE'ing.
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; CHECK-LABEL: @test5(
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define i32 @test5(i32 *%P) {
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%V1 = call i32 @func(i32* %P)
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%V2 = call i32 @func(i32* %P)
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%Diff = sub i32 %V1, %V2
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ret i32 %Diff
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; CHECK: ret i32 0
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}
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;; Trivial Store->load forwarding
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; CHECK-LABEL: @test6(
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define i32 @test6(i32 *%P) {
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store i32 42, i32* %P
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%V1 = load i32* %P
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ret i32 %V1
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; CHECK: ret i32 42
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}
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; CHECK-LABEL: @test6a(
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define i32 @test6a(i32 *%P, i1 %b) {
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store i32 42, i32* %P
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tail call void @llvm.assume(i1 %b)
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%V1 = load i32* %P
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ret i32 %V1
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; CHECK: ret i32 42
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}
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;; Trivial dead store elimination.
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; CHECK-LABEL: @test7(
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define void @test7(i32 *%P) {
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store i32 42, i32* %P
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store i32 45, i32* %P
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ret void
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; CHECK-NEXT: store i32 45
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; CHECK-NEXT: ret void
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}
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;; Readnone functions aren't invalidated by stores.
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; CHECK-LABEL: @test8(
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define i32 @test8(i32 *%P) {
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%V1 = call i32 @func(i32* %P) readnone
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store i32 4, i32* %P
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%V2 = call i32 @func(i32* %P) readnone
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%Diff = sub i32 %V1, %V2
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ret i32 %Diff
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; CHECK: ret i32 0
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}
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