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Merging r195493:

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------------------------------------------------------------------------
r195493 | arsenm | 2013-11-22 11:24:39 -0800 (Fri, 22 Nov 2013) | 6 lines

StructurizeCFG: Fix verification failure with some loops.

If the beginning of the loop was also the entry block
of the function, branches were inserted to the entry block
which isn't allowed. If this occurs, create a new dummy
function entry block that branches to the start of the loop.
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_34@195606 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bill Wendling 2013-11-25 05:23:10 +00:00
parent 215aad562c
commit e96466ecc0
2 changed files with 45 additions and 0 deletions
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14
lib/Transforms/Scalar/StructurizeCFG.cpp
View File

@ -779,6 +779,20 @@ void StructurizeCFG::handleLoops(bool ExitUseAllowed,
handleLoops(false, LoopEnd);
}
// If the start of the loop is the entry block, we can't branch to it so
// insert a new dummy entry block.
Function *LoopFunc = LoopStart->getParent();
if (LoopStart == &LoopFunc->getEntryBlock()) {
LoopStart->setName("entry.orig");
BasicBlock *NewEntry =
BasicBlock::Create(LoopStart->getContext(),
"entry",
LoopFunc,
LoopStart);
BranchInst::Create(LoopStart, NewEntry);
}
// Create an extra loop end node
LoopEnd = needPrefix(false);
BasicBlock *Next = needPostfix(LoopEnd, ExitUseAllowed);

31
test/Transforms/StructurizeCFG/no-branch-to-entry.ll Normal file
View File

@ -0,0 +1,31 @@
; RUN: opt -S -o - -structurizecfg < %s | FileCheck %s
; CHECK-LABEL: @no_branch_to_entry_undef(
; CHECK: entry:
; CHECK-NEXT: br label %entry.orig
define void @no_branch_to_entry_undef(i32 addrspace(1)* %out) {
entry:
br i1 undef, label %for.end, label %for.body
for.body: ; preds = %entry, %for.body
store i32 999, i32 addrspace(1)* %out, align 4
br label %for.body
for.end: ; preds = %Flow
ret void
}
; CHECK-LABEL: @no_branch_to_entry_true(
; CHECK: entry:
; CHECK-NEXT: br label %entry.orig
define void @no_branch_to_entry_true(i32 addrspace(1)* %out) {
entry:
br i1 true, label %for.end, label %for.body
for.body: ; preds = %entry, %for.body
store i32 999, i32 addrspace(1)* %out, align 4
br label %for.body
for.end: ; preds = %Flow
ret void
}