[llvm] r234891 - R600/SI: Fix verifier error caused by SIAnnotateControlFlow

[Tom Stellard]

Author: tstellar
Date: Tue Apr 14 09:36:45 2015
New Revision: 234891

URL: http://llvm.org/viewvc/llvm-project?rev=234891&view=rev
Log:
R600/SI: Fix verifier error caused by SIAnnotateControlFlow

This pass will always try to insert llvm.SI.ifbreak intrinsics
in the same block that its conditional value is computed in.  This is
a problem when conditions for breaks or continue are computed outside
of the loop, because the llvm.SI.ifbreak intrinsic ends up being inserted
outside of the loop.

This patch fixes this problem by inserting the llvm.SI.ifbreak
intrinsics in the loop header when the condition is computed outside
the loop.

Added:
    llvm/trunk/test/CodeGen/R600/si-annotate-cf.ll
Modified:
    llvm/trunk/lib/Target/R600/SIAnnotateControlFlow.cpp

Modified: llvm/trunk/lib/Target/R600/SIAnnotateControlFlow.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/R600/SIAnnotateControlFlow.cpp?rev=234891&r1=234890&r2=234891&view=diff
==============================================================================
--- llvm/trunk/lib/Target/R600/SIAnnotateControlFlow.cpp (original)
+++ llvm/trunk/lib/Target/R600/SIAnnotateControlFlow.cpp Tue Apr 14 09:36:45 2015
@@ -83,7 +83,7 @@ class SIAnnotateControlFlow : public Fun
 
   void insertElse(BranchInst *Term);
 
-  Value *handleLoopCondition(Value *Cond, PHINode *Broken);
+  Value *handleLoopCondition(Value *Cond, PHINode *Broken, llvm::Loop *L);
 
   void handleLoop(BranchInst *Term);
 
@@ -207,7 +207,8 @@ void SIAnnotateControlFlow::insertElse(B
 }
 
 /// \brief Recursively handle the condition leading to a loop
-Value *SIAnnotateControlFlow::handleLoopCondition(Value *Cond, PHINode *Broken) {
+Value *SIAnnotateControlFlow::handleLoopCondition(Value *Cond, PHINode *Broken,
+                                                  llvm::Loop *L) {
   if (PHINode *Phi = dyn_cast<PHINode>(Cond)) {
     BasicBlock *Parent = Phi->getParent();
     PHINode *NewPhi = PHINode::Create(Int64, 0, "", &Parent->front());
@@ -223,7 +224,7 @@ Value *SIAnnotateControlFlow::handleLoop
       }
 
       Phi->setIncomingValue(i, BoolFalse);
-      Value *PhiArg = handleLoopCondition(Incoming, Broken);
+      Value *PhiArg = handleLoopCondition(Incoming, Broken, L);
       NewPhi->addIncoming(PhiArg, From);
     }
 
@@ -253,7 +254,12 @@ Value *SIAnnotateControlFlow::handleLoop
 
   } else if (Instruction *Inst = dyn_cast<Instruction>(Cond)) {
     BasicBlock *Parent = Inst->getParent();
-    TerminatorInst *Insert = Parent->getTerminator();
+    Instruction *Insert;
+    if (L->contains(Inst)) {
+      Insert = Parent->getTerminator();
+    } else {
+      Insert = L->getHeader()->getFirstNonPHIOrDbgOrLifetime();
+    }
     Value *Args[] = { Cond, Broken };
     return CallInst::Create(IfBreak, Args, "", Insert);
 
@@ -265,14 +271,15 @@ Value *SIAnnotateControlFlow::handleLoop
 
 /// \brief Handle a back edge (loop)
 void SIAnnotateControlFlow::handleLoop(BranchInst *Term) {
+  BasicBlock *BB = Term->getParent();
+  llvm::Loop *L = LI->getLoopFor(BB);
   BasicBlock *Target = Term->getSuccessor(1);
   PHINode *Broken = PHINode::Create(Int64, 0, "", &Target->front());
 
   Value *Cond = Term->getCondition();
   Term->setCondition(BoolTrue);
-  Value *Arg = handleLoopCondition(Cond, Broken);
+  Value *Arg = handleLoopCondition(Cond, Broken, L);
 
-  BasicBlock *BB = Term->getParent();
   for (pred_iterator PI = pred_begin(Target), PE = pred_end(Target);
        PI != PE; ++PI) {
 

Added: llvm/trunk/test/CodeGen/R600/si-annotate-cf.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/R600/si-annotate-cf.ll?rev=234891&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/R600/si-annotate-cf.ll (added)
+++ llvm/trunk/test/CodeGen/R600/si-annotate-cf.ll Tue Apr 14 09:36:45 2015
@@ -0,0 +1,25 @@
+; RUN: llc < %s -march=amdgcn -mcpu=verde -verify-machineinstrs | FileCheck --check-prefix=SI --check-prefix=FUNC %s
+; RUN: llc < %s -march=amdgcn -mcpu=tonga -verify-machineinstrs | FileCheck --check-prefix=SI --check-prefix=FUNC %s
+
+; FUNC-LABEL: {{^}}break_inserted_outside_of_loop:
+
+; SI: [[LOOP_LABEL:[A-Z0-9]+]]:
+; Lowered break instructin:
+; SI: s_or_b64
+; Lowered Loop instruction:
+; SI: s_andn2_b64
+; s_cbranch_execnz [[LOOP_LABEL]]
+; SI: s_endpgm
+define void @break_inserted_outside_of_loop(i32 addrspace(1)* %out, i32 %a, i32 %b) {
+main_body:
+  %0 = and i32 %a, %b
+  %1 = trunc i32 %0 to i1
+  br label %ENDIF
+
+ENDLOOP:
+  store i32 0, i32 addrspace(1)* %out
+  ret void
+
+ENDIF:
+  br i1 %1, label %ENDLOOP, label %ENDIF
+}