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https://github.com/c64scene-ar/llvm-6502.git
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0814bd85dd
EarlyCSE is giving up on the current instruction immediately when it recognizes that the current instruction makes a previous store trivially dead. There's no reason to do this. Once the previous store has been deleted, it's perfectly legal to remember the value of the current store (for value forwarding) and the fact the store occurred (it could be dead too!). Reviewed by: Hal Differential Revision: http://reviews.llvm.org/D6301 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222241 91177308-0d34-0410-b5e6-96231b3b80d8
196 lines
4.3 KiB
LLVM
196 lines
4.3 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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;; Trivial DSE can't be performed across a readonly call. The call
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;; can observe the earlier write.
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; CHECK-LABEL: @test9(
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define i32 @test9(i32 *%P) {
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store i32 4, i32* %P
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%V1 = call i32 @func(i32* %P) readonly
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store i32 5, i32* %P
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ret i32 %V1
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; CHECK: store i32 4, i32* %P
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; CHECK-NEXT: %V1 = call i32 @func(i32* %P)
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; CHECK-NEXT: store i32 5, i32* %P
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; CHECK-NEXT: ret i32 %V1
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}
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;; Trivial DSE can be performed across a readnone call.
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; CHECK-LABEL: @test10
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define i32 @test10(i32 *%P) {
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store i32 4, i32* %P
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%V1 = call i32 @func(i32* %P) readnone
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store i32 5, i32* %P
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ret i32 %V1
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; CHECK-NEXT: %V1 = call i32 @func(i32* %P)
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; CHECK-NEXT: store i32 5, i32* %P
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; CHECK-NEXT: ret i32 %V1
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}
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;; Trivial dead store elimination - should work for an entire series of dead stores too.
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; CHECK-LABEL: @test11(
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define void @test11(i32 *%P) {
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store i32 42, i32* %P
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store i32 43, i32* %P
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store i32 44, 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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