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39c1af708a
Summary: This adds basic dead and redundant store elimination to NewGVN. Unlike our current DSE, it will happily do cross-block DSE if it meets our requirements. We get a bunch of DSE's simple.ll cases, and some stuff it doesn't. Unlike DSE, however, we only try to eliminate stores of the same value to the same memory location, not just general stores to the same memory location. Reviewers: davide Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D29149 llvm-svn: 293258
80 lines
2.6 KiB
LLVM
80 lines
2.6 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt < %s -basicaa -newgvn -S | FileCheck %s
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;; Most of these are borrowed from transforms/DSE/simple.ll
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;; NewGVN should be able to eliminate any stores of the same value that are actually redundnat.
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;; tmp5 is store of the same value to the same location as the load.
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define void @test12({ i32, i32 }* %x) nounwind {
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; CHECK-LABEL: @test12(
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; CHECK-NEXT: [[TMP4:%.*]] = getelementptr { i32, i32 }, { i32, i32 }* [[X:%.*]], i32 0, i32 0
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; CHECK-NEXT: [[TMP5:%.*]] = load i32, i32* [[TMP4]], align 4
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; CHECK-NEXT: [[TMP7:%.*]] = getelementptr { i32, i32 }, { i32, i32 }* [[X]], i32 0, i32 1
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; CHECK-NEXT: [[TMP8:%.*]] = load i32, i32* [[TMP7]], align 4
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; CHECK-NEXT: [[TMP17:%.*]] = sub i32 0, [[TMP8]]
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; CHECK-NEXT: store i32 [[TMP17]], i32* [[TMP7]], align 4
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; CHECK-NEXT: ret void
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;
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%tmp4 = getelementptr { i32, i32 }, { i32, i32 }* %x, i32 0, i32 0
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%tmp5 = load i32, i32* %tmp4, align 4
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%tmp7 = getelementptr { i32, i32 }, { i32, i32 }* %x, i32 0, i32 1
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%tmp8 = load i32, i32* %tmp7, align 4
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%tmp17 = sub i32 0, %tmp8
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store i32 %tmp5, i32* %tmp4, align 4
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store i32 %tmp17, i32* %tmp7, align 4
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ret void
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}
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; Remove redundant store if loaded value is in another block.
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define i32 @test26(i1 %c, i32* %p) {
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; CHECK-LABEL: @test26(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[V:%.*]] = load i32, i32* [[P:%.*]], align 4
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; CHECK-NEXT: br i1 [[C:%.*]], label [[BB1:%.*]], label [[BB2:%.*]]
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; CHECK: bb1:
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; CHECK-NEXT: br label [[BB3:%.*]]
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; CHECK: bb2:
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; CHECK-NEXT: br label [[BB3]]
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; CHECK: bb3:
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; CHECK-NEXT: ret i32 0
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;
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entry:
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%v = load i32, i32* %p, align 4
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br i1 %c, label %bb1, label %bb2
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bb1:
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br label %bb3
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bb2:
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store i32 %v, i32* %p, align 4
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br label %bb3
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bb3:
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ret i32 0
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}
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declare void @unknown_func()
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; Remove redundant store, which is in the same loop as the load.
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define i32 @test33(i1 %c, i32* %p, i32 %i) {
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; CHECK-LABEL: @test33(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: br label [[BB1:%.*]]
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; CHECK: bb1:
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; CHECK-NEXT: [[V:%.*]] = load i32, i32* [[P:%.*]], align 4
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; CHECK-NEXT: br label [[BB2:%.*]]
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; CHECK: bb2:
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; CHECK-NEXT: call void @unknown_func()
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; CHECK-NEXT: br i1 undef, label [[BB1]], label [[BB3:%.*]]
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; CHECK: bb3:
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; CHECK-NEXT: ret i32 0
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;
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entry:
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br label %bb1
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bb1:
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%v = load i32, i32* %p, align 4
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br label %bb2
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bb2:
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store i32 %v, i32* %p, align 4
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; Might read and overwrite value at %p, but doesn't matter.
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call void @unknown_func()
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br i1 undef, label %bb1, label %bb3
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bb3:
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ret i32 0
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}
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