[LoopUnroll] Unroll loops which have exit blocks to EH pads

We were overly cautious in our analysis of loops which have invokes
which unwind to EH pads.  The loop unroll transform is safe because it
only clones blocks in the loop body, it does not try to split critical
edges involving EH pads.  Instead, move the necessary safety check to
LoopUnswitch.

N.B. The safety check for loop unswitch is covered by an existing test
which fails without it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@268357 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/IR/CallSite.h b/include/llvm/IR/CallSite.h
index ad66cfbfaadc97af3b97425d4529331ef8b7122a..1a08434a31d77413f336983de4c2632ad8558eeb 100644 (file)
--- a/include/llvm/IR/CallSite.h
+++ b/include/llvm/IR/CallSite.h
@@ -426,6 +426,14 @@ public:
     CALLSITE_DELEGATE_SETTER(setDoesNotThrow());
   }
 
+  /// @brief Determine if the call can be duplicated.
+  bool cannotDuplicate() const {
+    CALLSITE_DELEGATE_GETTER(cannotDuplicate());
+  }
+  void setCannotDuplicate() {
+    CALLSITE_DELEGATE_GETTER(setCannotDuplicate());
+  }
+
   /// @brief Determine if the call is convergent.
   bool isConvergent() const {
     CALLSITE_DELEGATE_GETTER(isConvergent());

diff --git a/lib/Analysis/LoopInfo.cpp b/lib/Analysis/LoopInfo.cpp
index 277bd0dbb0f3813b3e56defed00aa2e6b8d84ef5..2ac1ae2e5cf6e3683bb1c0af425e9905770cab0d 100644 (file)
--- a/lib/Analysis/LoopInfo.cpp
+++ b/lib/Analysis/LoopInfo.cpp
@@ -195,23 +195,10 @@ bool Loop::isSafeToClone() const {
     if (isa<IndirectBrInst>(BB->getTerminator()))
       return false;
 
-    if (const InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
-      if (II->cannotDuplicate())
-        return false;
-      // Return false if any loop blocks contain invokes to EH-pads other than
-      // landingpads;  we don't know how to split those edges yet.
-      auto *FirstNonPHI = II->getUnwindDest()->getFirstNonPHI();
-      if (FirstNonPHI->isEHPad() && !isa<LandingPadInst>(FirstNonPHI))
-        return false;
-    }
-    for (Instruction &I : *BB) {
-      if (const CallInst *CI = dyn_cast<CallInst>(&I)) {
-        if (CI->cannotDuplicate())
+    for (Instruction &I : *BB)
+      if (auto CS = CallSite(&I))
+        if (CS.cannotDuplicate())
           return false;
-      }
-      if (I.getType()->isTokenTy() && I.isUsedOutsideOfBlock(BB))
-        return false;
-    }
   }
   return true;
 }

diff --git a/lib/Transforms/Scalar/LoopUnswitch.cpp b/lib/Transforms/Scalar/LoopUnswitch.cpp
index 310f41ed7df1697180e0d634fd685283926081b9..0e861b638d6295eb7b24b9e9ae3e6ad906c21c76 100644 (file)
--- a/lib/Transforms/Scalar/LoopUnswitch.cpp
+++ b/lib/Transforms/Scalar/LoopUnswitch.cpp
@@ -500,6 +500,11 @@ bool LoopUnswitch::processCurrentLoop() {
       if (!CS) continue;
       if (CS.hasFnAttr(Attribute::Convergent))
         return false;
+      // Return false if any loop blocks contain invokes whose predecessor edges
+      // we cannot split.
+      if (auto *II = dyn_cast<InvokeInst>(&I))
+        if (!II->getUnwindDest()->canSplitPredecessors())
+          return false;
     }
   }
 

diff --git a/test/Transforms/LoopUnroll/unroll-cleanuppad.ll b/test/Transforms/LoopUnroll/unroll-cleanuppad.ll
new file mode 100644 (file)
index 0000000..67f3194
--- /dev/null
+++ b/test/Transforms/LoopUnroll/unroll-cleanuppad.ll
@@ -0,0 +1,40 @@
+; RUN: opt -S -loop-unroll %s | FileCheck %s
+target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-pc-windows-msvc18.0.0"
+
+define void @test1() personality i32 (...)* @__CxxFrameHandler3 {
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.inc
+  %phi = phi i32 [ 0, %entry ], [ %inc, %for.inc ]
+  invoke void @callee(i32 %phi)
+          to label %for.inc unwind label %ehcleanup
+
+for.inc:                                          ; preds = %for.body
+  %inc = add nuw nsw i32 %phi, 1
+  %cmp = icmp slt i32 %inc, 3
+  br i1 %cmp, label %for.body, label %for.cond.cleanup
+
+for.cond.cleanup:                                 ; preds = %for.inc
+  call void @dtor()
+  ret void
+
+ehcleanup:                                        ; preds = %for.body
+  %cp = cleanuppad within none []
+  call void @dtor() [ "funclet"(token %cp) ]
+  cleanupret from %cp unwind to caller
+}
+
+; CHECK-LABEL: define void @test1(
+; CHECK: invoke void @callee(i32 0
+
+; CHECK: invoke void @callee(i32 1
+
+; CHECK: invoke void @callee(i32 2
+
+declare void @callee(i32)
+
+declare i32 @__CxxFrameHandler3(...)
+
+declare void @dtor()