[llvm] r355833 - [SimplifyCFG] Retain debug info when threading jumps with critical edges
Jeremy Morse via llvm-commits
llvm-commits at lists.llvm.org
Mon Mar 11 09:23:59 PDT 2019
Author: jmorse
Date: Mon Mar 11 09:23:59 2019
New Revision: 355833
URL: http://llvm.org/viewvc/llvm-project?rev=355833&view=rev
Log:
[SimplifyCFG] Retain debug info when threading jumps with critical edges
Fixes bug 38023: https://bugs.llvm.org/show_bug.cgi?id=38023
The SimplifyCFG pass will perform jump threading in some cases where
doing so is trivial and would simplify the CFG. When folding a series
of blocks with redundant conditional branches into an unconditional "critical
edge" block, it does not keep the debug location associated with the previous
conditional branch.
This patch fixes the bug described by copying the debug info from the
old conditional branch to the new unconditional branch instruction, and
adds a regression test for the SimplifyCFG pass that covers this case.
Patch by Stephen Tozer!
Differential Revision: https://reviews.llvm.org/D59206
Added:
llvm/trunk/test/Transforms/SimplifyCFG/debug-info-thread-phi.ll
Modified:
llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp
Modified: llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp?rev=355833&r1=355832&r2=355833&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp Mon Mar 11 09:23:59 2019
@@ -2209,7 +2209,8 @@ static bool FoldCondBranchOnPHI(BranchIn
BasicBlock *EdgeBB =
BasicBlock::Create(BB->getContext(), RealDest->getName() + ".critedge",
RealDest->getParent(), RealDest);
- BranchInst::Create(RealDest, EdgeBB);
+ BranchInst *CritEdgeBranch = BranchInst::Create(RealDest, EdgeBB);
+ CritEdgeBranch->setDebugLoc(BI->getDebugLoc());
// Update PHI nodes.
AddPredecessorToBlock(RealDest, EdgeBB, BB);
Added: llvm/trunk/test/Transforms/SimplifyCFG/debug-info-thread-phi.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SimplifyCFG/debug-info-thread-phi.ll?rev=355833&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/SimplifyCFG/debug-info-thread-phi.ll (added)
+++ llvm/trunk/test/Transforms/SimplifyCFG/debug-info-thread-phi.ll Mon Mar 11 09:23:59 2019
@@ -0,0 +1,38 @@
+; RUN: opt %s -debugify -simplifycfg -S | FileCheck %s
+; Tests Bug 37966
+
+define void @bar(i32 %aa) {
+; CHECK-LABEL: @bar(
+; CHECK: if.end.1.critedge:
+; CHECK: br label %if.end.1, !dbg ![[DBG:[0-9]+]]
+entry:
+ %aa.addr = alloca i32, align 4
+ %bb = alloca i32, align 4
+ store i32 %aa, i32* %aa.addr, align 4
+ store i32 0, i32* %bb, align 4
+ %tobool = icmp ne i32 %aa, 0
+ br i1 %tobool, label %if.then, label %if.end
+
+if.then: ; preds = %entry
+ call void @foo()
+ br label %if.end
+
+if.end: ; preds = %if.then, %entry
+ store i32 1, i32* %bb, align 4
+ br i1 %tobool, label %if.then.1, label %if.end.1
+
+if.then.1: ; preds = %if.end
+ call void @foo()
+ br label %if.end.1
+
+if.end.1: ; preds = %if.then.1, %if.end
+ store i32 2, i32* %bb, align 4
+ br label %for.end
+
+for.end: ; preds = %if.end.1
+ ret void
+}
+
+declare void @foo()
+
+; CHECK: ![[DBG]] = !DILocation(
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