[PATCH] D81607: BreakCriticalEdges for callbr indirect dests

[Nick Desaulniers via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rG88c965ba14cf: BreakCriticalEdges for callbr indirect dests (authored by nickdesaulniers).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D81607/new/

https://reviews.llvm.org/D81607

Files:
  llvm/lib/Transforms/Utils/BreakCriticalEdges.cpp
  llvm/test/Transforms/CallSiteSplitting/callsite-split-callbr.ll


Index: llvm/test/Transforms/CallSiteSplitting/callsite-split-callbr.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/CallSiteSplitting/callsite-split-callbr.ll
@@ -0,0 +1,53 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -callsite-splitting -S -o - < %s | FileCheck %s
+
+; Check that we can split the critical edge between Top and CallSiteBB, and
+; rewrite the first callbr's indirect destination correctly.
+
+define void @caller() {
+; CHECK-LABEL: @caller(
+; CHECK-NEXT:  Top:
+; CHECK-NEXT:    callbr void asm sideeffect "", "X,~{dirflag},~{fpsr},~{flags}"(i8* blockaddress(@caller, [[TOP_SPLIT:%.*]]))
+; CHECK-NEXT:    to label [[NEXTCOND:%.*]] [label %Top.split]
+; CHECK-LABEL: Top.split:
+; CHECK-NEXT:    call void @callee(i1 false)
+; CHECK-NEXT:    br label [[CALLSITEBB:%.*]]
+; CHECK-LABEL: NextCond:
+; CHECK-NEXT:    br label [[NEXTCOND_SPLIT:%.*]]
+; CHECK-LABEL: NextCond.split:
+; CHECK-NEXT:    call void @callee(i1 true)
+; CHECK-NEXT:    br label [[CALLSITEBB]]
+; CHECK-LABEL: CallSiteBB:
+; CHECK-NEXT:    [[PHI:%.*]] = phi i1 [ false, [[TOP_SPLIT]] ], [ true, [[NEXTCOND_SPLIT]] ]
+; CHECK-NEXT:    callbr void asm sideeffect "", "r,X,~{dirflag},~{fpsr},~{flags}"(i1 [[PHI]], i8* blockaddress(@caller, [[END2:%.*]]))
+; CHECK-NEXT:    to label [[END:%.*]] [label %End2]
+; CHECK-LABEL: End:
+; CHECK-NEXT:    ret void
+; CHECK-LABEL: End2:
+; CHECK-NEXT:    ret void
+;
+Top:
+  callbr void asm sideeffect "", "X,~{dirflag},~{fpsr},~{flags}"(i8* blockaddress(@caller, %CallSiteBB))
+  to label %NextCond [label %CallSiteBB]
+
+NextCond:
+  br label %CallSiteBB
+
+CallSiteBB:
+  %phi = phi i1 [0, %Top],[1, %NextCond]
+  call void @callee(i1 %phi)
+  callbr void asm sideeffect "", "r,X,~{dirflag},~{fpsr},~{flags}"(i1 %phi, i8* blockaddress(@caller, %End2))
+  to label %End [label %End2]
+
+End:
+  ret void
+End2:
+  ret void
+}
+
+define void @callee(i1 %b) {
+; CHECK-LABEL: @callee(
+; CHECK-NEXT:    ret void
+;
+  ret void
+}
Index: llvm/lib/Transforms/Utils/BreakCriticalEdges.cpp
===================================================================
--- llvm/lib/Transforms/Utils/BreakCriticalEdges.cpp
+++ llvm/lib/Transforms/Utils/BreakCriticalEdges.cpp
@@ -150,10 +150,6 @@
   // it in this generic function.
   if (DestBB->isEHPad()) return nullptr;
 
-  // Don't split the non-fallthrough edge from a callbr.
-  if (isa<CallBrInst>(TI) && SuccNum > 0)
-    return nullptr;
-
   if (Options.IgnoreUnreachableDests &&
       isa<UnreachableInst>(DestBB->getFirstNonPHIOrDbgOrLifetime()))
     return nullptr;
@@ -206,14 +202,14 @@
   BranchInst *NewBI = BranchInst::Create(DestBB, NewBB);
   NewBI->setDebugLoc(TI->getDebugLoc());
 
-  // Branch to the new block, breaking the edge.
-  TI->setSuccessor(SuccNum, NewBB);
-
   // Insert the block into the function... right after the block TI lives in.
   Function &F = *TIBB->getParent();
   Function::iterator FBBI = TIBB->getIterator();
   F.getBasicBlockList().insert(++FBBI, NewBB);
 
+  // Branch to the new block, breaking the edge.
+  TI->setSuccessor(SuccNum, NewBB);
+
   // If there are any PHI nodes in DestBB, we need to update them so that they
   // merge incoming values from NewBB instead of from TIBB.
   {


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