From 71fcd2d4d8d1ce17e12cdb82ce7cb96fe11ab70b Mon Sep 17 00:00:00 2001
From: Tom Stellard <thomas.stellard@amd.com>
Date: Tue, 14 Apr 2015 14:36:45 +0000
Subject: [PATCH] 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.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234891 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/R600/SIAnnotateControlFlow.cpp | 19 +++++++++++------
 test/CodeGen/R600/si-annotate-cf.ll       | 25 +++++++++++++++++++++++
 2 files changed, 38 insertions(+), 6 deletions(-)
 create mode 100644 test/CodeGen/R600/si-annotate-cf.ll

diff --git a/lib/Target/R600/SIAnnotateControlFlow.cpp b/lib/Target/R600/SIAnnotateControlFlow.cpp
index 79f6532f1d7..d39ab3f1850 100644
--- a/lib/Target/R600/SIAnnotateControlFlow.cpp
+++ b/lib/Target/R600/SIAnnotateControlFlow.cpp
@@ -83,7 +83,7 @@ class SIAnnotateControlFlow : public FunctionPass {
 
   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(BranchInst *Term) {
 }
 
 /// \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::handleLoopCondition(Value *Cond, PHINode *Broken)
       }
 
       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::handleLoopCondition(Value *Cond, PHINode *Broken)
 
   } 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::handleLoopCondition(Value *Cond, PHINode *Broken)
 
 /// \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) {
 
diff --git a/test/CodeGen/R600/si-annotate-cf.ll b/test/CodeGen/R600/si-annotate-cf.ll
new file mode 100644
index 00000000000..3f3098862ef
--- /dev/null
+++ b/test/CodeGen/R600/si-annotate-cf.ll
@@ -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
+}