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[GVNHoist] Fix: PR35222 gvn-hoist incorrectly erases load in case of a loop 

Reviewers:
    dberlin
    sebpop
    eli.friedman

Differential Revision: https://reviews.llvm.org/D41453

llvm-svn: 321789
This commit is contained in:
Aditya Kumar 2018-01-04 07:47:24 +00:00
parent fec26b0bbb
commit 1f90cae80f
2 changed files with 46 additions and 1 deletions
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2
llvm/lib/Transforms/Scalar/GVNHoist.cpp
View File

@ -648,7 +648,7 @@ private:
// track in a CHI. In the PDom walk, there can be values in the
// stack which are not control dependent e.g., nested loop.
if (si != RenameStack.end() && si->second.size() &&
DT->dominates(Pred, si->second.back()->getParent())) {
DT->properlyDominates(Pred, si->second.back()->getParent())) {
C.Dest = BB; // Assign the edge
C.I = si->second.pop_back_val(); // Assign the argument
DEBUG(dbgs() << "\nCHI Inserted in BB: " << C.Dest->getName()

45
llvm/test/Transforms/GVNHoist/pr35222-hoist-load.ll
View File

@ -1,4 +1,5 @@
; RUN: opt -S -gvn-hoist < %s | FileCheck %s
; CHECK-LABEL: build_tree
; CHECK: load
; CHECK: load
; Check that the load is not hoisted because the call can potentially
@ -23,3 +24,47 @@ do.end: ; preds = %do.body
}
declare i1 @pqdownheap(i32)
@i = external hidden unnamed_addr global i32, align 4
@j = external hidden unnamed_addr global [573 x i32], align 4
@v = external global i1
; CHECK-LABEL: test
; CHECK-LABEL: do.end
; CHECK: load
; Check that the load is not hoisted because the call can potentially
; modify the global
define i32 @test() {
entry:
br label %for.cond
for.cond:
%a3 = load volatile i1, i1* @v
br i1 %a3, label %for.body, label %while.end
for.body:
br label %if.then
if.then:
%tmp4 = load i32, i32* @i, align 4
br label %for.cond
while.end:
br label %do.body
do.body:
%tmp9 = load i32, i32* getelementptr inbounds ([573 x i32], [573 x i32]* @j,
i32 0, i32 1), align 4
%tmp10 = load i32, i32* @i, align 4
call void @fn()
%a1 = load volatile i1, i1* @v
br i1 %a1, label %do.body, label %do.end
do.end:
%tmp20 = load i32, i32* getelementptr inbounds ([573 x i32], [573 x i32]* @j,
i32 0, i32 1), align 4
ret i32 %tmp20
}
declare void @fn()