mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-08-01 17:29:33 +00:00
2276a7bc8e
to find opportunities for store-to-load forwarding or load CSE, in the same way that visitStore scans back to do DSE. Also, define a new helper function for testing whether the addresses of two memory accesses are known to have the same value, and use it in both visitStore and visitLoad. These two changes allow instcombine to eliminate loads in code produced by front-ends that frequently emit obviously redundant addressing for memory references. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@57608 91177308-0d34-0410-b5e6-96231b3b80d8
79 lines
2.0 KiB
LLVM
79 lines
2.0 KiB
LLVM
; This test makes sure that these instructions are properly eliminated.
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;
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; RUN: llvm-as < %s | opt -instcombine | llvm-dis | not grep load
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@X = constant i32 42 ; <i32*> [#uses=2]
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@X2 = constant i32 47 ; <i32*> [#uses=1]
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@Y = constant [2 x { i32, float }] [ { i32, float } { i32 12, float 1.000000e+00 }, { i32, float } { i32 37, float 0x3FF3B2FEC0000000 } ] ; <[2 x { i32, float }]*> [#uses=2]
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@Z = constant [2 x { i32, float }] zeroinitializer ; <[2 x { i32, float }]*> [#uses=1]
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define i32 @test1() {
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%B = load i32* @X ; <i32> [#uses=1]
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ret i32 %B
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}
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define float @test2() {
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%A = getelementptr [2 x { i32, float }]* @Y, i64 0, i64 1, i32 1 ; <float*> [#uses=1]
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%B = load float* %A ; <float> [#uses=1]
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ret float %B
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}
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define i32 @test3() {
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%A = getelementptr [2 x { i32, float }]* @Y, i64 0, i64 0, i32 0 ; <i32*> [#uses=1]
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%B = load i32* %A ; <i32> [#uses=1]
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ret i32 %B
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}
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define i32 @test4() {
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%A = getelementptr [2 x { i32, float }]* @Z, i64 0, i64 1, i32 0 ; <i32*> [#uses=1]
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%B = load i32* %A ; <i32> [#uses=1]
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ret i32 %B
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}
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define i32 @test5(i1 %C) {
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%Y = select i1 %C, i32* @X, i32* @X2 ; <i32*> [#uses=1]
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%Z = load i32* %Y ; <i32> [#uses=1]
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ret i32 %Z
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}
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define i32 @test7(i32 %X) {
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%V = getelementptr i32* null, i32 %X ; <i32*> [#uses=1]
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%R = load i32* %V ; <i32> [#uses=1]
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ret i32 %R
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}
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define i32 @test8(i32* %P) {
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store i32 1, i32* %P
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%X = load i32* %P ; <i32> [#uses=1]
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ret i32 %X
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}
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define i32 @test9(i32* %P) {
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%X = load i32* %P ; <i32> [#uses=1]
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%Y = load i32* %P ; <i32> [#uses=1]
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%Z = sub i32 %X, %Y ; <i32> [#uses=1]
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ret i32 %Z
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}
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define i32 @test10(i1 %C.upgrd.1, i32* %P, i32* %Q) {
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br i1 %C.upgrd.1, label %T, label %F
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T: ; preds = %0
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store i32 1, i32* %Q
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store i32 0, i32* %P
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br label %C
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F: ; preds = %0
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store i32 0, i32* %P
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br label %C
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C: ; preds = %F, %T
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%V = load i32* %P ; <i32> [#uses=1]
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ret i32 %V
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}
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define double @test11(double* %p) {
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%t0 = getelementptr double* %p, i32 1
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store double 2.0, double* %t0
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%t1 = getelementptr double* %p, i32 1
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%x = load double* %t1
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ret double %x
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}
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