[PATCH] D18282: AMDGPU/SI: Fix threshold calculation for branching when exec is zero

[Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rL263969: AMDGPU/SI: Fix threshold calculation for branching when exec is zero (authored by tstellar).

Changed prior to commit:
  http://reviews.llvm.org/D18282?vs=51069&id=51209#toc

Repository:
  rL LLVM

http://reviews.llvm.org/D18282

Files:
  llvm/trunk/lib/Target/AMDGPU/SILowerControlFlow.cpp
  llvm/trunk/test/CodeGen/AMDGPU/uniform-loop-inside-nonuniform.ll

Index: llvm/trunk/test/CodeGen/AMDGPU/uniform-loop-inside-nonuniform.ll
===================================================================
--- llvm/trunk/test/CodeGen/AMDGPU/uniform-loop-inside-nonuniform.ll
+++ llvm/trunk/test/CodeGen/AMDGPU/uniform-loop-inside-nonuniform.ll
@@ -24,5 +24,39 @@
   ret void
 }
 
+;CHECK-LABEL: {{^}}test2:
+;CHECK: s_and_saveexec_b64
+;CHECK: s_xor_b64
+;CHECK-NEXT: s_cbranch_execz
+define void @test2(i32 addrspace(1)* %out, i32 %a, i32 %b) {
+main_body:
+  %tid = call i32 @llvm.amdgcn.workitem.id.x() #1
+  %cc = icmp eq i32 %tid, 0
+  br i1 %cc, label %done1, label %if
+
+if:
+  %cmp = icmp eq i32 %a, 0
+  br i1 %cmp, label %done0, label %loop_body
+
+loop_body:
+  %counter = phi i32 [ 0, %if ], [0, %done0], [ %incr, %loop_body ]
+
+  ; Prevent the loop from being optimized out
+  call void asm sideeffect "", "" ()
+
+  %incr = add i32 %counter, 1
+  %lc = icmp sge i32 %incr, 1000
+  br i1 %lc, label %done1, label %loop_body
+
+done0:
+  %cmp0 = icmp eq i32 %b, 0
+  br i1 %cmp0, label %done1, label %loop_body
+
+done1:
+  ret void
+}
+
+declare i32 @llvm.amdgcn.workitem.id.x() #1
+
 attributes #0 = { "ShaderType"="0" }
 attributes #1 = { nounwind readonly }
Index: llvm/trunk/lib/Target/AMDGPU/SILowerControlFlow.cpp
===================================================================
--- llvm/trunk/lib/Target/AMDGPU/SILowerControlFlow.cpp
+++ llvm/trunk/lib/Target/AMDGPU/SILowerControlFlow.cpp
@@ -130,10 +130,12 @@
 
   unsigned NumInstr = 0;
 
-  for (MachineBasicBlock *MBB = From; MBB != To && !MBB->succ_empty();
-       MBB = *MBB->succ_begin()) {
+  for (MachineFunction::iterator MBBI = MachineFunction::iterator(From),
+                                 ToI = MachineFunction::iterator(To); MBBI != ToI; ++MBBI) {
 
-    for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end();
+    MachineBasicBlock &MBB = *MBBI;
+
+    for (MachineBasicBlock::iterator I = MBB.begin(), E = MBB.end();
          NumInstr < SkipThreshold && I != E; ++I) {
 
       if (I->isBundle() || !I->isBundled()) {


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