Add test case for r311511

This also changes the TailDuplicator to be configured explicitely
pre/post regalloc rather than relying on the isSSA() flag. This was
necessary to have `llc -run-pass` work reliably.

llvm-svn: 311520

3 files changed, 8 insertions, 4 deletions

diff --git a/llvm/lib/CodeGen/MachineBlockPlacement.cpp b/llvm/lib/CodeGen/MachineBlockPlacement.cpp
index 65330308dad..c30f306a169 100644
--- a/llvm/lib/CodeGen/MachineBlockPlacement.cpp
+++ b/llvm/lib/CodeGen/MachineBlockPlacement.cpp
@@ -2729,7 +2729,8 @@ bool MachineBlockPlacement::runOnMachineFunction(MachineFunction &MF) {
     MPDT = &getAnalysis<MachinePostDominatorTree>();
     if (MF.getFunction()->optForSize())
       TailDupSize = 1;
-    TailDup.initMF(MF, MBPI, /* LayoutMode */ true, TailDupSize);
+    bool PreRegAlloc = false;
+    TailDup.initMF(MF, PreRegAlloc, MBPI, /* LayoutMode */ true, TailDupSize);
     precomputeTriangleChains();
   }
 
diff --git a/llvm/lib/CodeGen/TailDuplication.cpp b/llvm/lib/CodeGen/TailDuplication.cpp
index 489a607eb17..131b9a22768 100644
--- a/llvm/lib/CodeGen/TailDuplication.cpp
+++ b/llvm/lib/CodeGen/TailDuplication.cpp
@@ -52,7 +52,10 @@ bool TailDuplicatePass::runOnMachineFunction(MachineFunction &MF) {
 
   auto MBPI = &getAnalysis<MachineBranchProbabilityInfo>();
 
-  Duplicator.initMF(MF, MBPI, /* LayoutMode */ false);
+  // TODO: Querying isSSA() to determine pre-/post-regalloc is fragile, better
+  // split this into two passes instead.
+  bool PreRegAlloc = MF.getRegInfo().isSSA();
+  Duplicator.initMF(MF, PreRegAlloc, MBPI, /* LayoutMode */ false);
 
   bool MadeChange = false;
   while (Duplicator.tailDuplicateBlocks())
diff --git a/llvm/lib/CodeGen/TailDuplicator.cpp b/llvm/lib/CodeGen/TailDuplicator.cpp
index 0f22040f3ae..bd3a20f936d 100644
--- a/llvm/lib/CodeGen/TailDuplicator.cpp
+++ b/llvm/lib/CodeGen/TailDuplicator.cpp
@@ -75,7 +75,7 @@ static cl::opt<bool>
 static cl::opt<unsigned> TailDupLimit("tail-dup-limit", cl::init(~0U),
                                       cl::Hidden);
 
-void TailDuplicator::initMF(MachineFunction &MFin,
+void TailDuplicator::initMF(MachineFunction &MFin, bool PreRegAlloc,
                             const MachineBranchProbabilityInfo *MBPIin,
                             bool LayoutModeIn, unsigned TailDupSizeIn) {
   MF = &MFin;
@@ -89,7 +89,7 @@ void TailDuplicator::initMF(MachineFunction &MFin,
   assert(MBPI != nullptr && "Machine Branch Probability Info required");
 
   LayoutMode = LayoutModeIn;
-  PreRegAlloc = MRI->isSSA();
+  this->PreRegAlloc = PreRegAlloc;
 }
 
 static void VerifyPHIs(MachineFunction &MF, bool CheckExtra) {