From: Hal Finkel <hfinkel@anl.gov>
Date: Tue, 21 May 2013 14:21:09 +0000 (+0000)
Subject: Fix PPC branch selection for counter-based branches
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=75e9ee8b7fc2b7c91239f4b9b8d77087fd8ea4e4;p=oota-llvm.git

Fix PPC branch selection for counter-based branches

Although I had added some support for the BDZ/BDNZ branches into the selector
(in r158204), I had not correctly adjusted the condition at the top of the
loop. As a result, these branches were still essentially unsupported.

This fixes PR16086. Unfortunately, any test case would be very large (because
it would need to force the loop backedge to exceed the range of the 16-bit
immediate).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@182385 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Target/PowerPC/PPCBranchSelector.cpp b/lib/Target/PowerPC/PPCBranchSelector.cpp
index bd1c3786811..3e608ca8f67 100644
--- a/lib/Target/PowerPC/PPCBranchSelector.cpp
+++ b/lib/Target/PowerPC/PPCBranchSelector.cpp
@@ -112,15 +112,21 @@ bool PPCBSel::runOnMachineFunction(MachineFunction &Fn) {
       unsigned MBBStartOffset = 0;
       for (MachineBasicBlock::iterator I = MBB.begin(), E = MBB.end();
            I != E; ++I) {
-        if (I->getOpcode() != PPC::BCC || I->getOperand(2).isImm()) {
+        MachineBasicBlock *Dest = 0;
+        if (I->getOpcode() == PPC::BCC && !I->getOperand(2).isImm())
+          Dest = I->getOperand(2).getMBB();
+        else if ((I->getOpcode() == PPC::BDNZ8 || I->getOpcode() == PPC::BDNZ ||
+                  I->getOpcode() == PPC::BDZ8  || I->getOpcode() == PPC::BDZ) &&
+                 !I->getOperand(0).isImm())
+          Dest = I->getOperand(0).getMBB();
+
+        if (!Dest) {
           MBBStartOffset += TII->GetInstSizeInBytes(I);
           continue;
         }
         
         // Determine the offset from the current branch to the destination
         // block.
-        MachineBasicBlock *Dest = I->getOperand(2).getMBB();
-        
         int BranchSize;
         if (Dest->getNumber() <= MBB.getNumber()) {
           // If this is a backwards branch, the delta is the offset from the