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llvm-project/llvm/test/Transforms/InstCombine/gepphigep.ll

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Add support for combining GEPs across PHI nodes Currently LLVM will generally merge GEPs. This allows backends to use more complex addressing modes. In some cases this is not happening because there is PHI inbetween the two GEPs: GEP1--\ |-->PHI1-->GEP3 GEP2--/ This patch checks to see if GEP1 and GEP2 are similiar enough that they can be cloned (GEP12) in GEP3's BB, allowing GEP->GEP merging (GEP123): GEP1--\ --\ --\ |-->PHI1-->GEP3 ==> |-->PHI2->GEP12->GEP3 == > |-->PHI2->GEP123 GEP2--/ --/ --/ This also breaks certain use chains that are preventing GEP->GEP merges that the the existing instcombine would merge otherwise. Tests included. llvm-svn: 209843
2014-05-30 04:29:47 +08:00
; RUN: opt -instcombine -S < %s | FileCheck %s
%struct1 = type { %struct2*, i32, i32, i32 }
%struct2 = type { i32, i32 }
define i32 @test1(%struct1* %dm, i1 %tmp4, i64 %tmp9, i64 %tmp19) {
bb:
%tmp = getelementptr inbounds %struct1* %dm, i64 0, i32 0
%tmp1 = load %struct2** %tmp, align 8
br i1 %tmp4, label %bb1, label %bb2
bb1:
%tmp10 = getelementptr inbounds %struct2* %tmp1, i64 %tmp9
%tmp11 = getelementptr inbounds %struct2* %tmp10, i64 0, i32 0
store i32 0, i32* %tmp11, align 4
br label %bb3
bb2:
%tmp20 = getelementptr inbounds %struct2* %tmp1, i64 %tmp19
%tmp21 = getelementptr inbounds %struct2* %tmp20, i64 0, i32 0
store i32 0, i32* %tmp21, align 4
br label %bb3
bb3:
%phi = phi %struct2* [ %tmp10, %bb1 ], [ %tmp20, %bb2 ]
%tmp24 = getelementptr inbounds %struct2* %phi, i64 0, i32 1
%tmp25 = load i32* %tmp24, align 4
ret i32 %tmp25
; CHECK-LABEL: @test1(
; CHECK: getelementptr inbounds %struct2* %tmp1, i64 %tmp9, i32 0
; CHECK: getelementptr inbounds %struct2* %tmp1, i64 %tmp19, i32 0
; CHECK: %[[PHI:[0-9A-Za-z]+]] = phi i64 [ %tmp9, %bb1 ], [ %tmp19, %bb2 ]
; CHECK: getelementptr inbounds %struct2* %tmp1, i64 %[[PHI]], i32 1
}
define i32 @test2(%struct1* %dm, i1 %tmp4, i64 %tmp9, i64 %tmp19) {
bb:
%tmp = getelementptr inbounds %struct1* %dm, i64 0, i32 0
%tmp1 = load %struct2** %tmp, align 8
%tmp10 = getelementptr inbounds %struct2* %tmp1, i64 %tmp9
%tmp11 = getelementptr inbounds %struct2* %tmp10, i64 0, i32 0
store i32 0, i32* %tmp11, align 4
%tmp20 = getelementptr inbounds %struct2* %tmp1, i64 %tmp19
%tmp21 = getelementptr inbounds %struct2* %tmp20, i64 0, i32 0
store i32 0, i32* %tmp21, align 4
%tmp24 = getelementptr inbounds %struct2* %tmp10, i64 0, i32 1
%tmp25 = load i32* %tmp24, align 4
ret i32 %tmp25
; CHECK-LABEL: @test2(
; CHECK: getelementptr inbounds %struct2* %tmp1, i64 %tmp9, i32 0
; CHECK: getelementptr inbounds %struct2* %tmp1, i64 %tmp19, i32 0
; CHECK: getelementptr inbounds %struct2* %tmp1, i64 %tmp9, i32 1
}