From 15121ca0d18e6a0f6a16f8a696f4efc3782dc965 Mon Sep 17 00:00:00 2001
From: Jakob Stoklund Olesen <stoklund@2pi.dk>
Date: Fri, 10 Aug 2012 03:23:27 +0000
Subject: [PATCH] Update edge weights correctly in replaceSuccessor().
When replacing Old with New, it can happen that New is already a
successor. Add the old and new edge weights instead of creating a
duplicate edge.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161653 91177308-0d34-0410-b5e6-96231b3b80d8
---
lib/CodeGen/MachineBasicBlock.cpp | 42 ++++++++++++++++++++++++-------
test/CodeGen/X86/br-fold.ll | 2 +-
2 files changed, 34 insertions(+), 10 deletions(-)
diff --git a/lib/CodeGen/MachineBasicBlock.cpp b/lib/CodeGen/MachineBasicBlock.cpp
index 151b4021681..fd4cb5fab0b 100644
--- a/lib/CodeGen/MachineBasicBlock.cpp
+++ b/lib/CodeGen/MachineBasicBlock.cpp
@@ -478,18 +478,42 @@ MachineBasicBlock::removeSuccessor(succ_iterator I) {
void MachineBasicBlock::replaceSuccessor(MachineBasicBlock *Old,
MachineBasicBlock *New) {
- uint32_t weight = 0;
- succ_iterator SI = std::find(Successors.begin(), Successors.end(), Old);
+ if (Old == New)
+ return;
- // If Weight list is empty it means we don't use it (disabled optimization).
- if (!Weights.empty()) {
- weight_iterator WI = getWeightIterator(SI);
- weight = *WI;
+ succ_iterator E = succ_end();
+ succ_iterator NewI = E;
+ succ_iterator OldI = E;
+ for (succ_iterator I = succ_begin(); I != E; ++I) {
+ if (*I == Old) {
+ OldI = I;
+ if (NewI != E)
+ break;
+ }
+ if (*I == New) {
+ NewI = I;
+ if (OldI != E)
+ break;
+ }
+ }
+ assert(OldI != E && "Old is not a successor of this block");
+ Old->removePredecessor(this);
+
+ // If New isn't already a successor, let it take Old's place.
+ if (NewI == E) {
+ New->addPredecessor(this);
+ *OldI = New;
+ return;
}
- // Update the successor information.
- removeSuccessor(SI);
- addSuccessor(New, weight);
+ // New is already a successor.
+ // Update its weight instead of adding a duplicate edge.
+ if (!Weights.empty()) {
+ weight_iterator OldWI = getWeightIterator(OldI);
+ *getWeightIterator(NewI) += *OldWI;
+ Weights.erase(OldWI);
+ }
+ Successors.erase(OldI);
}
void MachineBasicBlock::addPredecessor(MachineBasicBlock *pred) {
diff --git a/test/CodeGen/X86/br-fold.ll b/test/CodeGen/X86/br-fold.ll
index 2c371949380..52234630116 100644
--- a/test/CodeGen/X86/br-fold.ll
+++ b/test/CodeGen/X86/br-fold.ll
@@ -1,7 +1,7 @@
; RUN: llc -march=x86-64 < %s | FileCheck %s
; CHECK: orq
-; CHECK-NEXT: LBB0_1
+; CHECK-NEXT: %bb8.i329
@_ZN11xercesc_2_513SchemaSymbols21fgURI_SCHEMAFORSCHEMAE = external constant [33 x i16], align 32 ; <[33 x i16]*> [#uses=1]
@_ZN11xercesc_2_56XMLUni16fgNotationStringE = external constant [9 x i16], align 16 ; <[9 x i16]*> [#uses=1]