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-rw-r--r--include/llvm/Transforms/Utils/Local.h6
-rw-r--r--lib/Transforms/Scalar/CodeGenPrepare.cpp2
-rw-r--r--lib/Transforms/Scalar/JumpThreading.cpp2
-rw-r--r--lib/Transforms/Scalar/SimplifyCFGPass.cpp2
-rw-r--r--lib/Transforms/Utils/Local.cpp24
-rw-r--r--lib/Transforms/Utils/SimplifyCFG.cpp2
-rw-r--r--test/Transforms/SimplifyCFG/dce-cond-after-folding-terminator.ll52
7 files changed, 78 insertions, 12 deletions
diff --git a/include/llvm/Transforms/Utils/Local.h b/include/llvm/Transforms/Utils/Local.h
index e61dcb347c..c9d2916821 100644
--- a/include/llvm/Transforms/Utils/Local.h
+++ b/include/llvm/Transforms/Utils/Local.h
@@ -43,8 +43,10 @@ template<typename T> class SmallVectorImpl;
/// constant value, convert it into an unconditional branch to the constant
/// destination. This is a nontrivial operation because the successors of this
/// basic block must have their PHI nodes updated.
-///
-bool ConstantFoldTerminator(BasicBlock *BB);
+/// Also calls RecursivelyDeleteTriviallyDeadInstructions() on any branch/switch
+/// conditions and indirectbr addresses this might make dead if
+/// DeleteDeadConditions is true.
+bool ConstantFoldTerminator(BasicBlock *BB, bool DeleteDeadConditions = false);
//===----------------------------------------------------------------------===//
// Local dead code elimination.
diff --git a/lib/Transforms/Scalar/CodeGenPrepare.cpp b/lib/Transforms/Scalar/CodeGenPrepare.cpp
index 0184390185..483bfe3655 100644
--- a/lib/Transforms/Scalar/CodeGenPrepare.cpp
+++ b/lib/Transforms/Scalar/CodeGenPrepare.cpp
@@ -147,7 +147,7 @@ bool CodeGenPrepare::runOnFunction(Function &F) {
if (!DisableBranchOpts) {
MadeChange = false;
for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
- MadeChange |= ConstantFoldTerminator(BB);
+ MadeChange |= ConstantFoldTerminator(BB, true);
if (MadeChange)
ModifiedDT = true;
diff --git a/lib/Transforms/Scalar/JumpThreading.cpp b/lib/Transforms/Scalar/JumpThreading.cpp
index 5a8f4ca192..cf18ff040b 100644
--- a/lib/Transforms/Scalar/JumpThreading.cpp
+++ b/lib/Transforms/Scalar/JumpThreading.cpp
@@ -706,7 +706,7 @@ bool JumpThreading::ProcessBlock(BasicBlock *BB) {
DEBUG(dbgs() << " In block '" << BB->getName()
<< "' folding terminator: " << *BB->getTerminator() << '\n');
++NumFolds;
- ConstantFoldTerminator(BB);
+ ConstantFoldTerminator(BB, true);
return true;
}
diff --git a/lib/Transforms/Scalar/SimplifyCFGPass.cpp b/lib/Transforms/Scalar/SimplifyCFGPass.cpp
index 1137c2b23f..eccafea3aa 100644
--- a/lib/Transforms/Scalar/SimplifyCFGPass.cpp
+++ b/lib/Transforms/Scalar/SimplifyCFGPass.cpp
@@ -163,7 +163,7 @@ static bool MarkAliveBlocks(BasicBlock *BB,
Changed = true;
}
- Changed |= ConstantFoldTerminator(BB);
+ Changed |= ConstantFoldTerminator(BB, true);
for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB); SI != SE; ++SI)
Worklist.push_back(*SI);
} while (!Worklist.empty());
diff --git a/lib/Transforms/Utils/Local.cpp b/lib/Transforms/Utils/Local.cpp
index 12e15b07c7..f5a8adacd5 100644
--- a/lib/Transforms/Utils/Local.cpp
+++ b/lib/Transforms/Utils/Local.cpp
@@ -44,11 +44,14 @@ using namespace llvm;
// Local constant propagation.
//
-// ConstantFoldTerminator - If a terminator instruction is predicated on a
-// constant value, convert it into an unconditional branch to the constant
-// destination.
-//
-bool llvm::ConstantFoldTerminator(BasicBlock *BB) {
+/// ConstantFoldTerminator - If a terminator instruction is predicated on a
+/// constant value, convert it into an unconditional branch to the constant
+/// destination. This is a nontrivial operation because the successors of this
+/// basic block must have their PHI nodes updated.
+/// Also calls RecursivelyDeleteTriviallyDeadInstructions() on any branch/switch
+/// conditions and indirectbr addresses this might make dead if
+/// DeleteDeadConditions is true.
+bool llvm::ConstantFoldTerminator(BasicBlock *BB, bool DeleteDeadConditions) {
TerminatorInst *T = BB->getTerminator();
IRBuilder<> Builder(T);
@@ -89,7 +92,10 @@ bool llvm::ConstantFoldTerminator(BasicBlock *BB) {
// Replace the conditional branch with an unconditional one.
Builder.CreateBr(Dest1);
+ Value *Cond = BI->getCondition();
BI->eraseFromParent();
+ if (DeleteDeadConditions)
+ RecursivelyDeleteTriviallyDeadInstructions(Cond);
return true;
}
return false;
@@ -152,7 +158,10 @@ bool llvm::ConstantFoldTerminator(BasicBlock *BB) {
}
// Delete the old switch.
- BB->getInstList().erase(SI);
+ Value *Cond = SI->getCondition();
+ SI->eraseFromParent();
+ if (DeleteDeadConditions)
+ RecursivelyDeleteTriviallyDeadInstructions(Cond);
return true;
}
@@ -186,7 +195,10 @@ bool llvm::ConstantFoldTerminator(BasicBlock *BB) {
else
IBI->getDestination(i)->removePredecessor(IBI->getParent());
}
+ Value *Address = IBI->getAddress();
IBI->eraseFromParent();
+ if (DeleteDeadConditions)
+ RecursivelyDeleteTriviallyDeadInstructions(Address);
// If we didn't find our destination in the IBI successor list, then we
// have undefined behavior. Replace the unconditional branch with an
diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp
index 2c032d5d12..5ab9a2877c 100644
--- a/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -2651,7 +2651,7 @@ bool SimplifyCFGOpt::run(BasicBlock *BB) {
// Check to see if we can constant propagate this terminator instruction
// away...
- Changed |= ConstantFoldTerminator(BB);
+ Changed |= ConstantFoldTerminator(BB, true);
// Check for and eliminate duplicate PHI nodes in this block.
Changed |= EliminateDuplicatePHINodes(BB);
diff --git a/test/Transforms/SimplifyCFG/dce-cond-after-folding-terminator.ll b/test/Transforms/SimplifyCFG/dce-cond-after-folding-terminator.ll
new file mode 100644
index 0000000000..3996efd82b
--- /dev/null
+++ b/test/Transforms/SimplifyCFG/dce-cond-after-folding-terminator.ll
@@ -0,0 +1,52 @@
+; RUN: opt -S <%s -simplifycfg | FileCheck %s
+
+define void @test_br(i32 %x) {
+entry:
+; CHECK: @test_br
+; CHECK-NEXT: entry:
+; CHECK-NEXT: ret void
+ %cmp = icmp eq i32 %x, 10
+ br i1 %cmp, label %if.then, label %if.then
+
+if.then: ; preds = %entry
+ br label %if.end
+
+if.end: ; preds = %if.else, %if.then
+ ret void
+}
+
+define void @test_switch(i32 %x) nounwind {
+entry:
+; CHECK: @test_switch
+; CHECK-NEXT: entry:
+; CHECK-NEXT: ret void
+ %rem = srem i32 %x, 3
+ switch i32 %rem, label %sw.bb [
+ i32 1, label %sw.bb
+ i32 10, label %sw.bb
+ ]
+
+sw.bb: ; preds = %sw.default, %entry, %entry
+ br label %sw.epilog
+
+sw.epilog: ; preds = %sw.bb
+ ret void
+}
+
+define void @test_indirectbr(i32 %x) {
+entry:
+; CHECK: @test_indirectbr
+; CHECK-NEXT: entry:
+; Ideally this should now check:
+; CHK-NEXT: ret void
+; But that doesn't happen yet. Instead:
+; CHECK-NEXT: br label %L1
+
+ %label = bitcast i8* blockaddress(@test_indirectbr, %L1) to i8*
+ indirectbr i8* %label, [label %L1, label %L2]
+
+L1: ; preds = %entry
+ ret void
+L2: ; preds = %entry
+ ret void
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-06-04 09:12:06 +0000