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[PredicateInfo] Place predicate info after assume
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Place the ssa.copy instructions for assumes after the assume,
instead of before it. Both options are valid, but placing them
afterwards prevents assumes from being replaced with assume(true).
This fixes https://bugs.llvm.org/show_bug.cgi?id=37541 in NewGVN
and will avoid a similar issue in SCCP when we handle more
predicate infos.

Differential Revision: https://reviews.llvm.org/D83631
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@nikic
nikic committed Jul 13, 2020
1 parent 4b626dd commit 353fa44
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Showing 4 changed files with 24 additions and 22 deletions.
10 changes: 6 additions & 4 deletions llvm/lib/Transforms/Utils/PredicateInfo.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -205,14 +205,14 @@ struct ValueDFS_Compare {
// numbering will say the placed predicaeinfos should go first (IE
// LN_beginning), so we won't be in this function. For assumes, we will end
// up here, beause we need to order the def we will place relative to the
// assume. So for the purpose of ordering, we pretend the def is the assume
// because that is where we will insert the info.
// assume. So for the purpose of ordering, we pretend the def is right
// after the assume, because that is where we will insert the info.
if (!VD.U) {
assert(VD.PInfo &&
"No def, no use, and no predicateinfo should not occur");
assert(isa<PredicateAssume>(VD.PInfo) &&
"Middle of block should only occur for assumes");
return cast<PredicateAssume>(VD.PInfo)->AssumeInst;
return cast<PredicateAssume>(VD.PInfo)->AssumeInst->getNextNode();
}
return nullptr;
}
Expand Down Expand Up @@ -621,7 +621,9 @@ Value *PredicateInfoBuilder::materializeStack(unsigned int &Counter,
auto *PAssume = dyn_cast<PredicateAssume>(ValInfo);
assert(PAssume &&
"Should not have gotten here without it being an assume");
IRBuilder<> B(PAssume->AssumeInst);
// Insert the predicate directly after the assume. While it also holds
// directly before it, assume(i1 true) is not a useful fact.
IRBuilder<> B(PAssume->AssumeInst->getNextNode());
Function *IF = getCopyDeclaration(F.getParent(), Op->getType());
if (IF->users().empty())
PI.CreatedDeclarations.insert(IF);
Expand Down
10 changes: 5 additions & 5 deletions llvm/test/Transforms/NewGVN/assume-equal.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -7,7 +7,7 @@ define float @_Z1if(float %p) {
; CHECK-NEXT: [[P_ADDR:%.*]] = alloca float, align 4
; CHECK-NEXT: store float [[P:%.*]], float* [[P_ADDR]], align 4
; CHECK-NEXT: [[CMP:%.*]] = fcmp ueq float [[P]], 3.000000e+00
; CHECK-NEXT: call void @llvm.assume(i1 true)
; CHECK-NEXT: call void @llvm.assume(i1 [[CMP]])
; CHECK-NEXT: ret float [[P]]
;
entry:
Expand All @@ -26,7 +26,7 @@ define i32 @_Z1ii(i32 %p) {
; CHECK-LABEL: @_Z1ii(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[P:%.*]], 42
; CHECK-NEXT: call void @llvm.assume(i1 true)
; CHECK-NEXT: call void @llvm.assume(i1 [[CMP]])
; CHECK-NEXT: br i1 true, label [[BB2:%.*]], label [[BB2]]
; CHECK: bb2:
; CHECK-NEXT: br i1 true, label [[BB2]], label [[BB2]]
Expand All @@ -50,7 +50,7 @@ define i32 @_Z1ij(i32 %p) {
; CHECK-LABEL: @_Z1ij(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[P:%.*]], 42
; CHECK-NEXT: call void @llvm.assume(i1 true)
; CHECK-NEXT: call void @llvm.assume(i1 [[CMP]])
; CHECK-NEXT: br i1 true, label [[BB2:%.*]], label [[BB2]]
; CHECK: bb2:
; CHECK-NEXT: call void @llvm.assume(i1 true)
Expand All @@ -76,10 +76,10 @@ define i32 @_Z1ik(i32 %p) {
; CHECK-LABEL: @_Z1ik(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[P:%.*]], 42
; CHECK-NEXT: call void @llvm.assume(i1 true)
; CHECK-NEXT: call void @llvm.assume(i1 [[CMP]])
; CHECK-NEXT: br i1 true, label [[BB2:%.*]], label [[BB3:%.*]]
; CHECK: bb2:
; CHECK-NEXT: call void @llvm.assume(i1 true)
; CHECK-NEXT: call void @llvm.assume(i1 false)
; CHECK-NEXT: ret i32 15
; CHECK: bb3:
; CHECK-NEXT: store i8 undef, i8* null, align 1
Expand Down
4 changes: 2 additions & 2 deletions llvm/test/Transforms/NewGVN/assumes.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,7 @@
define i32 @test1(i32 %arg) {
; CHECK-LABEL: @test1(
; CHECK-NEXT: [[CMP:%.*]] = icmp sge i32 [[ARG:%.*]], 5
; CHECK-NEXT: call void @llvm.assume(i1 true)
; CHECK-NEXT: call void @llvm.assume(i1 [[CMP]])
; CHECK-NEXT: ret i32 [[ARG]]
;
%cmp = icmp sge i32 %arg, 5
Expand All @@ -18,7 +18,7 @@ define i32 @test2(i32 %arg, i1 %b) {
; CHECK: bb:
; CHECK-NEXT: [[A:%.*]] = phi i32 [ 1, [[TMP0:%.*]] ], [ 2, [[BB]] ]
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[ARG:%.*]], [[A]]
; CHECK-NEXT: call void @llvm.assume(i1 true)
; CHECK-NEXT: call void @llvm.assume(i1 [[CMP]])
; CHECK-NEXT: br i1 [[B:%.*]], label [[BB]], label [[END:%.*]]
; CHECK: end:
; CHECK-NEXT: ret i32 [[ARG]]
Expand Down
22 changes: 11 additions & 11 deletions llvm/test/Transforms/Util/PredicateInfo/testandor.ll
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -print-predicateinfo < %s 2>&1 | FileCheck %s
; RUN: opt -print-predicateinfo -disable-output < %s 2>&1 | FileCheck %s

declare void @foo(i1)
declare void @bar(i32)
Expand Down Expand Up @@ -136,18 +136,18 @@ define void @testandassume(i32 %x, i32 %y) {
; CHECK-NEXT: [[XZ:%.*]] = icmp eq i32 [[X:%.*]], 0
; CHECK-NEXT: [[YZ:%.*]] = icmp eq i32 [[Y:%.*]], 0
; CHECK-NEXT: [[Z:%.*]] = and i1 [[XZ]], [[YZ]]
; CHECK: [[TMP1:%.*]] = call i1 @llvm.ssa.copy.{{.+}}(i1 [[XZ]])
; CHECK: [[TMP2:%.*]] = call i32 @llvm.ssa.copy.{{.+}}(i32 [[X]])
; CHECK-NEXT: call void @llvm.assume(i1 [[Z]])
; CHECK: [[TMP1:%.*]] = call i1 @llvm.ssa.copy.{{.+}}(i1 [[Z]])
; CHECK: [[TMP2:%.*]] = call i32 @llvm.ssa.copy.{{.+}}(i32 [[Y]])
; CHECK: [[TMP3:%.*]] = call i1 @llvm.ssa.copy.{{.+}}(i1 [[YZ]])
; CHECK: [[TMP4:%.*]] = call i32 @llvm.ssa.copy.{{.+}}(i32 [[Y]])
; CHECK: [[TMP5:%.*]] = call i1 @llvm.ssa.copy.{{.+}}(i1 [[Z]])
; CHECK-NEXT: call void @llvm.assume(i1 [[TMP5]])
; CHECK: [[DOT0:%.*]] = call i1 @llvm.ssa.copy.{{.+}}(i1 [[TMP1]])
; CHECK: [[DOT01:%.*]] = call i32 @llvm.ssa.copy.{{.+}}(i32 [[TMP2]])
; CHECK: [[TMP4:%.*]] = call i32 @llvm.ssa.copy.{{.+}}(i32 [[X]])
; CHECK: [[TMP5:%.*]] = call i1 @llvm.ssa.copy.{{.+}}(i1 [[XZ]])
; CHECK: [[DOT0:%.*]] = call i1 @llvm.ssa.copy.{{.+}}(i1 [[TMP5]])
; CHECK: [[DOT01:%.*]] = call i32 @llvm.ssa.copy.{{.+}}(i32 [[TMP4]])
; CHECK: [[DOT02:%.*]] = call i1 @llvm.ssa.copy.{{.+}}(i1 [[TMP3]])
; CHECK: [[DOT03:%.*]] = call i32 @llvm.ssa.copy.{{.+}}(i32 [[TMP4]])
; CHECK: [[DOT04:%.*]] = call i1 @llvm.ssa.copy.{{.+}}(i1 [[TMP5]])
; CHECK-NEXT: br i1 [[TMP5]], label [[BOTH:%.*]], label [[NOPE:%.*]]
; CHECK: [[DOT03:%.*]] = call i32 @llvm.ssa.copy.{{.+}}(i32 [[TMP2]])
; CHECK: [[DOT04:%.*]] = call i1 @llvm.ssa.copy.{{.+}}(i1 [[TMP1]])
; CHECK-NEXT: br i1 [[TMP1]], label [[BOTH:%.*]], label [[NOPE:%.*]]
; CHECK: both:
; CHECK-NEXT: call void @foo(i1 [[DOT0]])
; CHECK-NEXT: call void @foo(i1 [[DOT02]])
Expand Down

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