[llvm] r347683 - [PartialInliner] Make PHIs free in cost computation.

[Florian Hahn via llvm-commits]

Author: fhahn
Date: Tue Nov 27 10:17:27 2018
New Revision: 347683

URL: http://llvm.org/viewvc/llvm-project?rev=347683&view=rev
Log:
[PartialInliner] Make PHIs free in cost computation.

InlineCost also treats them as free and the current implementation
can cause assertion failures if PHI nodes are moved outside the region
from entry BBs to the region.

It also updates the code to use the instructionsWithoutDebug iterator.

Reviewers: davidxl, davide, vsk, graham-yiu-huawei

Reviewed By: davidxl

Differential Revision: https://reviews.llvm.org/D54748

Added:
    llvm/trunk/test/Transforms/CodeExtractor/PartialInlineEntryPHICost.ll
Modified:
    llvm/trunk/lib/Transforms/IPO/PartialInlining.cpp

Modified: llvm/trunk/lib/Transforms/IPO/PartialInlining.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/PartialInlining.cpp?rev=347683&r1=347682&r2=347683&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/IPO/PartialInlining.cpp (original)
+++ llvm/trunk/lib/Transforms/IPO/PartialInlining.cpp Tue Nov 27 10:17:27 2018
@@ -834,42 +834,41 @@ bool PartialInlinerImpl::shouldPartialIn
 int PartialInlinerImpl::computeBBInlineCost(BasicBlock *BB) {
   int InlineCost = 0;
   const DataLayout &DL = BB->getParent()->getParent()->getDataLayout();
-  for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
-    if (isa<DbgInfoIntrinsic>(I))
-      continue;
-
-    switch (I->getOpcode()) {
+  for (Instruction &I : BB->instructionsWithoutDebug()) {
+    // Skip free instructions.
+    switch (I.getOpcode()) {
     case Instruction::BitCast:
     case Instruction::PtrToInt:
     case Instruction::IntToPtr:
     case Instruction::Alloca:
+    case Instruction::PHI:
       continue;
     case Instruction::GetElementPtr:
-      if (cast<GetElementPtrInst>(I)->hasAllZeroIndices())
+      if (cast<GetElementPtrInst>(&I)->hasAllZeroIndices())
         continue;
       break;
     default:
       break;
     }
 
-    IntrinsicInst *IntrInst = dyn_cast<IntrinsicInst>(I);
+    IntrinsicInst *IntrInst = dyn_cast<IntrinsicInst>(&I);
     if (IntrInst) {
       if (IntrInst->getIntrinsicID() == Intrinsic::lifetime_start ||
           IntrInst->getIntrinsicID() == Intrinsic::lifetime_end)
         continue;
     }
 
-    if (CallInst *CI = dyn_cast<CallInst>(I)) {
+    if (CallInst *CI = dyn_cast<CallInst>(&I)) {
       InlineCost += getCallsiteCost(CallSite(CI), DL);
       continue;
     }
 
-    if (InvokeInst *II = dyn_cast<InvokeInst>(I)) {
+    if (InvokeInst *II = dyn_cast<InvokeInst>(&I)) {
       InlineCost += getCallsiteCost(CallSite(II), DL);
       continue;
     }
 
-    if (SwitchInst *SI = dyn_cast<SwitchInst>(I)) {
+    if (SwitchInst *SI = dyn_cast<SwitchInst>(&I)) {
       InlineCost += (SI->getNumCases() + 1) * InlineConstants::InstrCost;
       continue;
     }

Added: llvm/trunk/test/Transforms/CodeExtractor/PartialInlineEntryPHICost.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/CodeExtractor/PartialInlineEntryPHICost.ll?rev=347683&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/CodeExtractor/PartialInlineEntryPHICost.ll (added)
+++ llvm/trunk/test/Transforms/CodeExtractor/PartialInlineEntryPHICost.ll Tue Nov 27 10:17:27 2018
@@ -0,0 +1,40 @@
+; RUN: opt < %s -partial-inliner -S | FileCheck %s
+; RUN: opt < %s -passes=partial-inliner -S | FileCheck %s
+
+; Check that we do not overcompute the outlined region cost, where the PHIs in
+; the outlined region entry (BB4) are moved outside the region by CodeExtractor.
+
+define i32 @bar(i32 %arg) {
+bb:
+  %tmp = icmp slt i32 %arg, 0
+  br i1 %tmp, label %bb1, label %bb2
+
+bb1:
+  br i1 undef, label %bb4, label %bb2
+
+bb2:                                              ; preds = %bb, %bb1
+  br i1 undef, label %bb4, label %bb5
+
+bb4:                                              ; preds = %bb1, %bb2
+  %xx1 = phi i32 [ 1, %bb1 ], [ 9, %bb2 ]
+  %xx2 = phi i32 [ 1, %bb1 ], [ 9, %bb2 ]
+  %xx3 = phi i32 [ 1, %bb1 ], [ 9, %bb2 ]
+  tail call void (...) @foo() #2
+  br label %bb5
+
+bb5:                                              ; preds = %bb4, %bb2
+  %tmp6 = phi i32 [ 1, %bb2 ], [ 9, %bb4 ]
+  ret i32 %tmp6
+}
+
+declare void @foo(...)
+
+define i32 @dummy_caller(i32 %arg) {
+bb:
+; CHECK-LABEL: @dummy_caller
+; CHECK: br i1
+; CHECK: br i1
+; CHECK: call void @bar.1.
+  %tmp = tail call i32 @bar(i32 %arg)
+  ret i32 %tmp
+}