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clang-p2996/llvm/test/Transforms/InstCombine/select-cmp-br.ll
Bjorn Pettersson e5027cfbcc [InstCombine] Avoid faulty combines of select-cmp-br 
Summary:
When InstCombine is optimizing certain select-cmp-br patterns
it replaces the result of the select in uses outside of the
basic block containing the select. This is only legal if the
path from the select to the outside use is disjoint from all
other paths out from the originating basic block.

The problem found was that InstCombiner::replacedSelectWithOperand
did not consider the case when both edges out from the br pointed
to the same label. In that case the paths aren't disjoint and the
transformation is illegal. This patch avoids the faulty rewrites
by verifying that there is a single flow to the successor where
we want to replace uses.

Reviewers: llvm-commits, spatel, majnemer

Differential Revision: https://reviews.llvm.org/D30455

llvm-svn: 296752
2017-03-02 15:18:58 +00:00

264 lines
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; Replace a 'select' with 'or' in 'select - cmp [eq|ne] - br' sequence
; RUN: opt -instcombine -S < %s | FileCheck %s
%struct.S = type { i64*, i32, i32 }
%C = type <{ %struct.S }>
declare void @bar(%struct.S*)
declare void @foobar()
define void @test1(%C* %arg) {
; CHECK-LABEL: @test1(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP:%.*]] = getelementptr inbounds [[C:%.*]], %C* [[ARG:%.*]], i64 0, i32 0, i32 0
; CHECK-NEXT: [[M:%.*]] = load i64*, i64** [[TMP]], align 8
; CHECK-NEXT: [[TMP1:%.*]] = getelementptr inbounds [[C]], %C* [[ARG]], i64 1, i32 0, i32 0
; CHECK-NEXT: [[N:%.*]] = load i64*, i64** [[TMP1]], align 8
; CHECK-NEXT: [[TMP71:%.*]] = icmp eq %C* [[ARG]], null
; CHECK-NEXT: [[NOT_TMP5:%.*]] = icmp ne i64* [[M]], [[N]]
; CHECK-NEXT: [[TMP7:%.*]] = or i1 [[TMP71]], [[NOT_TMP5]]
; CHECK-NEXT: br i1 [[TMP7]], label [[BB10:%.*]], label [[BB8:%.*]]
; CHECK: bb:
; CHECK-NEXT: ret void
; CHECK: bb8:
; CHECK-NEXT: [[TMP9:%.*]] = getelementptr inbounds [[C]], %C* [[ARG]], i64 0, i32 0
; CHECK-NEXT: tail call void @bar(%struct.S* [[TMP9]])
; CHECK-NEXT: br label [[BB:%.*]]
; CHECK: bb10:
; CHECK-NEXT: [[TMP2:%.*]] = getelementptr inbounds i64, i64* [[M]], i64 9
; CHECK-NEXT: [[TMP3:%.*]] = bitcast i64* [[TMP2]] to i64 (%C*)**
; CHECK-NEXT: [[TMP4:%.*]] = load i64 (%C*)*, i64 (%C*)** [[TMP3]], align 8
; CHECK-NEXT: [[TMP11:%.*]] = tail call i64 [[TMP4]](%C* [[ARG]])
; CHECK-NEXT: br label [[BB]]
;
entry:
%tmp = getelementptr inbounds %C, %C* %arg, i64 0, i32 0, i32 0
%m = load i64*, i64** %tmp, align 8
%tmp1 = getelementptr inbounds %C, %C* %arg, i64 1, i32 0, i32 0
%n = load i64*, i64** %tmp1, align 8
%tmp2 = getelementptr inbounds i64, i64* %m, i64 9
%tmp3 = bitcast i64* %tmp2 to i64 (%C*)**
%tmp4 = load i64 (%C*)*, i64 (%C*)** %tmp3, align 8
%tmp5 = icmp eq i64* %m, %n
%tmp6 = select i1 %tmp5, %C* %arg, %C* null
%tmp7 = icmp eq %C* %tmp6, null
br i1 %tmp7, label %bb10, label %bb8
bb: ; preds = %bb10, %bb8
ret void
bb8: ; preds = %entry
%tmp9 = getelementptr inbounds %C, %C* %tmp6, i64 0, i32 0
tail call void @bar(%struct.S* %tmp9)
br label %bb
bb10: ; preds = %entry
%tmp11 = tail call i64 %tmp4(%C* %arg)
br label %bb
}
define void @test2(%C* %arg) {
; CHECK-LABEL: @test2(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP:%.*]] = getelementptr inbounds [[C:%.*]], %C* [[ARG:%.*]], i64 0, i32 0, i32 0
; CHECK-NEXT: [[M:%.*]] = load i64*, i64** [[TMP]], align 8
; CHECK-NEXT: [[TMP1:%.*]] = getelementptr inbounds [[C]], %C* [[ARG]], i64 1, i32 0, i32 0
; CHECK-NEXT: [[N:%.*]] = load i64*, i64** [[TMP1]], align 8
; CHECK-NEXT: [[TMP5:%.*]] = icmp eq i64* [[M]], [[N]]
; CHECK-NEXT: [[TMP71:%.*]] = icmp eq %C* [[ARG]], null
; CHECK-NEXT: [[TMP7:%.*]] = or i1 [[TMP5]], [[TMP71]]
; CHECK-NEXT: br i1 [[TMP7]], label [[BB10:%.*]], label [[BB8:%.*]]
; CHECK: bb:
; CHECK-NEXT: ret void
; CHECK: bb8:
; CHECK-NEXT: [[TMP9:%.*]] = getelementptr inbounds [[C]], %C* [[ARG]], i64 0, i32 0
; CHECK-NEXT: tail call void @bar(%struct.S* [[TMP9]])
; CHECK-NEXT: br label [[BB:%.*]]
; CHECK: bb10:
; CHECK-NEXT: [[TMP2:%.*]] = getelementptr inbounds i64, i64* [[M]], i64 9
; CHECK-NEXT: [[TMP3:%.*]] = bitcast i64* [[TMP2]] to i64 (%C*)**
; CHECK-NEXT: [[TMP4:%.*]] = load i64 (%C*)*, i64 (%C*)** [[TMP3]], align 8
; CHECK-NEXT: [[TMP11:%.*]] = tail call i64 [[TMP4]](%C* [[ARG]])
; CHECK-NEXT: br label [[BB]]
;
entry:
%tmp = getelementptr inbounds %C, %C* %arg, i64 0, i32 0, i32 0
%m = load i64*, i64** %tmp, align 8
%tmp1 = getelementptr inbounds %C, %C* %arg, i64 1, i32 0, i32 0
%n = load i64*, i64** %tmp1, align 8
%tmp2 = getelementptr inbounds i64, i64* %m, i64 9
%tmp3 = bitcast i64* %tmp2 to i64 (%C*)**
%tmp4 = load i64 (%C*)*, i64 (%C*)** %tmp3, align 8
%tmp5 = icmp eq i64* %m, %n
%tmp6 = select i1 %tmp5, %C* null, %C* %arg
%tmp7 = icmp eq %C* %tmp6, null
br i1 %tmp7, label %bb10, label %bb8
bb: ; preds = %bb10, %bb8
ret void
bb8: ; preds = %entry
%tmp9 = getelementptr inbounds %C, %C* %tmp6, i64 0, i32 0
tail call void @bar(%struct.S* %tmp9)
br label %bb
bb10: ; preds = %entry
%tmp11 = tail call i64 %tmp4(%C* %arg)
br label %bb
}
define void @test3(%C* %arg) {
; CHECK-LABEL: @test3(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP:%.*]] = getelementptr inbounds [[C:%.*]], %C* [[ARG:%.*]], i64 0, i32 0, i32 0
; CHECK-NEXT: [[M:%.*]] = load i64*, i64** [[TMP]], align 8
; CHECK-NEXT: [[TMP1:%.*]] = getelementptr inbounds [[C]], %C* [[ARG]], i64 1, i32 0, i32 0
; CHECK-NEXT: [[N:%.*]] = load i64*, i64** [[TMP1]], align 8
; CHECK-NEXT: [[TMP71:%.*]] = icmp eq %C* [[ARG]], null
; CHECK-NEXT: [[NOT_TMP5:%.*]] = icmp ne i64* [[M]], [[N]]
; CHECK-NEXT: [[TMP7:%.*]] = or i1 [[TMP71]], [[NOT_TMP5]]
; CHECK-NEXT: br i1 [[TMP7]], label [[BB10:%.*]], label [[BB8:%.*]]
; CHECK: bb:
; CHECK-NEXT: ret void
; CHECK: bb8:
; CHECK-NEXT: [[TMP9:%.*]] = getelementptr inbounds [[C]], %C* [[ARG]], i64 0, i32 0
; CHECK-NEXT: tail call void @bar(%struct.S* [[TMP9]])
; CHECK-NEXT: br label [[BB:%.*]]
; CHECK: bb10:
; CHECK-NEXT: [[TMP2:%.*]] = getelementptr inbounds i64, i64* [[M]], i64 9
; CHECK-NEXT: [[TMP3:%.*]] = bitcast i64* [[TMP2]] to i64 (%C*)**
; CHECK-NEXT: [[TMP4:%.*]] = load i64 (%C*)*, i64 (%C*)** [[TMP3]], align 8
; CHECK-NEXT: [[TMP11:%.*]] = tail call i64 [[TMP4]](%C* [[ARG]])
; CHECK-NEXT: br label [[BB]]
;
entry:
%tmp = getelementptr inbounds %C, %C* %arg, i64 0, i32 0, i32 0
%m = load i64*, i64** %tmp, align 8
%tmp1 = getelementptr inbounds %C, %C* %arg, i64 1, i32 0, i32 0
%n = load i64*, i64** %tmp1, align 8
%tmp2 = getelementptr inbounds i64, i64* %m, i64 9
%tmp3 = bitcast i64* %tmp2 to i64 (%C*)**
%tmp4 = load i64 (%C*)*, i64 (%C*)** %tmp3, align 8
%tmp5 = icmp eq i64* %m, %n
%tmp6 = select i1 %tmp5, %C* %arg, %C* null
%tmp7 = icmp ne %C* %tmp6, null
br i1 %tmp7, label %bb8, label %bb10
bb: ; preds = %bb10, %bb8
ret void
bb8: ; preds = %entry
%tmp9 = getelementptr inbounds %C, %C* %tmp6, i64 0, i32 0
tail call void @bar(%struct.S* %tmp9)
br label %bb
bb10: ; preds = %entry
%tmp11 = tail call i64 %tmp4(%C* %arg)
br label %bb
}
define void @test4(%C* %arg) {
; CHECK-LABEL: @test4(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP:%.*]] = getelementptr inbounds [[C:%.*]], %C* [[ARG:%.*]], i64 0, i32 0, i32 0
; CHECK-NEXT: [[M:%.*]] = load i64*, i64** [[TMP]], align 8
; CHECK-NEXT: [[TMP1:%.*]] = getelementptr inbounds [[C]], %C* [[ARG]], i64 1, i32 0, i32 0
; CHECK-NEXT: [[N:%.*]] = load i64*, i64** [[TMP1]], align 8
; CHECK-NEXT: [[TMP5:%.*]] = icmp eq i64* [[M]], [[N]]
; CHECK-NEXT: [[TMP71:%.*]] = icmp eq %C* [[ARG]], null
; CHECK-NEXT: [[TMP7:%.*]] = or i1 [[TMP5]], [[TMP71]]
; CHECK-NEXT: br i1 [[TMP7]], label [[BB10:%.*]], label [[BB8:%.*]]
; CHECK: bb:
; CHECK-NEXT: ret void
; CHECK: bb8:
; CHECK-NEXT: [[TMP9:%.*]] = getelementptr inbounds [[C]], %C* [[ARG]], i64 0, i32 0
; CHECK-NEXT: tail call void @bar(%struct.S* [[TMP9]])
; CHECK-NEXT: br label [[BB:%.*]]
; CHECK: bb10:
; CHECK-NEXT: [[TMP2:%.*]] = getelementptr inbounds i64, i64* [[M]], i64 9
; CHECK-NEXT: [[TMP3:%.*]] = bitcast i64* [[TMP2]] to i64 (%C*)**
; CHECK-NEXT: [[TMP4:%.*]] = load i64 (%C*)*, i64 (%C*)** [[TMP3]], align 8
; CHECK-NEXT: [[TMP11:%.*]] = tail call i64 [[TMP4]](%C* [[ARG]])
; CHECK-NEXT: br label [[BB]]
;
entry:
%tmp = getelementptr inbounds %C, %C* %arg, i64 0, i32 0, i32 0
%m = load i64*, i64** %tmp, align 8
%tmp1 = getelementptr inbounds %C, %C* %arg, i64 1, i32 0, i32 0
%n = load i64*, i64** %tmp1, align 8
%tmp2 = getelementptr inbounds i64, i64* %m, i64 9
%tmp3 = bitcast i64* %tmp2 to i64 (%C*)**
%tmp4 = load i64 (%C*)*, i64 (%C*)** %tmp3, align 8
%tmp5 = icmp eq i64* %m, %n
%tmp6 = select i1 %tmp5, %C* null, %C* %arg
%tmp7 = icmp ne %C* %tmp6, null
br i1 %tmp7, label %bb8, label %bb10
bb: ; preds = %bb10, %bb8
ret void
bb8: ; preds = %entry
%tmp9 = getelementptr inbounds %C, %C* %tmp6, i64 0, i32 0
tail call void @bar(%struct.S* %tmp9)
br label %bb
bb10: ; preds = %entry
%tmp11 = tail call i64 %tmp4(%C* %arg)
br label %bb
}
define void @test5(%C* %arg, i1 %arg1) {
; CHECK-LABEL: @test5(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP21:%.*]] = icmp eq %C* [[ARG:%.*]], null
; CHECK-NEXT: [[TMP2:%.*]] = or i1 [[TMP21]], [[ARG1:%.*]]
; CHECK-NEXT: br i1 [[TMP2]], label [[BB5:%.*]], label [[BB3:%.*]]
; CHECK: bb:
; CHECK-NEXT: ret void
; CHECK: bb3:
; CHECK-NEXT: [[TMP4:%.*]] = getelementptr inbounds [[C:%.*]], %C* [[ARG]], i64 0, i32 0
; CHECK-NEXT: tail call void @bar(%struct.S* [[TMP4]])
; CHECK-NEXT: br label [[BB:%.*]]
; CHECK: bb5:
; CHECK-NEXT: tail call void @foobar()
; CHECK-NEXT: br label [[BB]]
;
entry:
%tmp = select i1 %arg1, %C* null, %C* %arg
%tmp2 = icmp ne %C* %tmp, null
br i1 %tmp2, label %bb3, label %bb5
bb: ; preds = %bb5, %bb3
ret void
bb3: ; preds = %entry
%tmp4 = getelementptr inbounds %C, %C* %tmp, i64 0, i32 0
tail call void @bar(%struct.S* %tmp4)
br label %bb
bb5: ; preds = %entry
tail call void @foobar()
br label %bb
}
; Negative test. Must not trigger the select-cmp-br combine because the result
; of the select is used in both flows following the br (the special case where
; the conditional branch has the same target for both flows).
define i32 @test6(i32 %arg, i1 %arg1) {
; CHECK-LABEL: @test6(
; CHECK-NEXT: entry:
; CHECK-NEXT: br i1 undef, label [[BB:%.*]], label [[BB]]
; CHECK: bb:
; CHECK-NEXT: [[TMP:%.*]] = select i1 [[ARG1:%.*]], i32 [[ARG:%.*]], i32 0
; CHECK-NEXT: ret i32 [[TMP]]
;
entry:
%tmp = select i1 %arg1, i32 %arg, i32 0
%tmp2 = icmp eq i32 %tmp, 0
br i1 %tmp2, label %bb, label %bb
bb: ; preds = %entry, %entry
ret i32 %tmp
}
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