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NewGVN: Make sure we don't incorrectly use PredicateInfo when doing PHI of ops 

Summary: When we backtranslate expressions, we can't use the predicateinfo, since we are evaluating them in a different context.

Reviewers: davide, mcrosier

Subscribers: sanjoy, Prazek, llvm-commits

Differential Revision: https://reviews.llvm.org/D37174

llvm-svn: 312352
This commit is contained in:
Daniel Berlin 2017-09-01 19:20:18 +00:00
parent 75557fa024
commit 86932104db
2 changed files with 54 additions and 3 deletions
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13
llvm/lib/Transforms/Scalar/NewGVN.cpp
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@ -1782,10 +1782,15 @@ const Expression *NewGVN::performSymbolicCmpEvaluation(Instruction *I) const {
if (PI == LastPredInfo) if (PI == LastPredInfo)
continue; continue;
LastPredInfo = PI; LastPredInfo = PI;
// In phi of ops cases, we may have predicate info that we are evaluating
// TODO: Along the false edge, we may know more things too, like icmp of // in a different context.
if (!DT->dominates(PBranch->To, getBlockForValue(I)))
continue;
// TODO: Along the false edge, we may know more things too, like
// icmp of
// same operands is false. // same operands is false.
// TODO: We only handle actual comparison conditions below, not and/or. // TODO: We only handle actual comparison conditions below, not
// and/or.
auto *BranchCond = dyn_cast<CmpInst>(PBranch->Condition); auto *BranchCond = dyn_cast<CmpInst>(PBranch->Condition);
if (!BranchCond) if (!BranchCond)
continue; continue;
@ -2533,11 +2538,13 @@ NewGVN::makePossiblePhiOfOps(Instruction *I,
// and make sure anything that tries to add it's DFS number is // and make sure anything that tries to add it's DFS number is
// redirected to the instruction we are making a phi of ops // redirected to the instruction we are making a phi of ops
// for. // for.
TempToBlock.insert({ValueOp, PredBB});
InstrDFS.insert({ValueOp, IDFSNum}); InstrDFS.insert({ValueOp, IDFSNum});
const Expression *E = performSymbolicEvaluation(ValueOp, Visited); const Expression *E = performSymbolicEvaluation(ValueOp, Visited);
InstrDFS.erase(ValueOp); InstrDFS.erase(ValueOp);
AllTempInstructions.erase(ValueOp); AllTempInstructions.erase(ValueOp);
ValueOp->deleteValue(); ValueOp->deleteValue();
TempToBlock.erase(ValueOp);
if (MemAccess) if (MemAccess)
TempToMemory.erase(ValueOp); TempToMemory.erase(ValueOp);
if (!E) if (!E)

44
llvm/test/Transforms/NewGVN/pr34135.ll Normal file
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@ -0,0 +1,44 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -newgvn -enable-phi-of-ops=true -S | FileCheck %s
;; Make sure we don't incorrectly use predicateinfo to simplify phi of ops cases
source_filename = "pr34135.ll"
define void @snork(i32 %arg) {
; CHECK-LABEL: @snork(
; CHECK-NEXT: bb:
; CHECK-NEXT: [[TMP:%.*]] = sext i32 [[ARG:%.*]] to i64
; CHECK-NEXT: br label [[BB1:%.*]]
; CHECK: bb1:
; CHECK-NEXT: [[TMP2:%.*]] = phi i64 [ 0, [[BB:%.*]] ], [ [[TMP3:%.*]], [[BB1]] ]
; CHECK-NEXT: [[TMP3]] = add i64 [[TMP2]], 1
; CHECK-NEXT: [[TMP4:%.*]] = icmp slt i64 [[TMP3]], [[TMP]]
; CHECK-NEXT: br i1 [[TMP4]], label [[BB1]], label [[BB7:%.*]]
; CHECK: bb5:
; CHECK-NEXT: [[TMP6:%.*]] = icmp sgt i64 [[TMP]], 1
; CHECK-NEXT: br i1 [[TMP6]], label [[BB7]], label [[BB9:%.*]]
; CHECK: bb7:
; CHECK-NEXT: br label [[BB5:%.*]]
; CHECK: bb9:
; CHECK-NEXT: unreachable
;
bb:
%tmp = sext i32 %arg to i64
br label %bb1
bb1: ; preds = %bb1, %bb
%tmp2 = phi i64 [ 0, %bb ], [ %tmp3, %bb1 ]
%tmp3 = add i64 %tmp2, 1
%tmp4 = icmp slt i64 %tmp3, %tmp
br i1 %tmp4, label %bb1, label %bb7
bb5: ; preds = %bb7
%tmp6 = icmp sgt i64 %tmp8, 1
br i1 %tmp6, label %bb7, label %bb9
bb7: ; preds = %bb5, %bb1
%tmp8 = phi i64 [ undef, %bb5 ], [ %tmp, %bb1 ]
br label %bb5
bb9: ; preds = %bb5
unreachable
}