[Reassociation] Place moved instructions after landing pads

Reassociation's NegateValue moved instructions to the beginning of
blocks (after PHIs) without checking for exception handling pads.
It's possible for reassociation to move something into an exception
handling block so we need to make sure we don't move things too early
in the block.  This change advances the insertion point past any
exception handling pads.

If the block we want to move into contains a catchswitch, we cannot
move into it.  In that case just create a new neg as if we had not
found an existing neg to move.

Differential Revision: https://reviews.llvm.org/D61089

llvm-svn: 360262

llvm/lib/Transforms/Scalar/Reassociate.cpp

@@ -861,17 +861,39 @@ static Value *NegateValue(Value *V, Instruction *BI,
     if (TheNeg->getParent()->getParent() != BI->getParent()->getParent())
       continue;
 
+    bool FoundCatchSwitch = false;
+
     BasicBlock::iterator InsertPt;
     if (Instruction *InstInput = dyn_cast<Instruction>(V)) {
       if (InvokeInst *II = dyn_cast<InvokeInst>(InstInput)) {
         InsertPt = II->getNormalDest()->begin();
       } else {
         InsertPt = ++InstInput->getIterator();
       }
-      while (isa<PHINode>(InsertPt)) ++InsertPt;
+
+      const BasicBlock *BB = InsertPt->getParent();
+
+      // Make sure we don't move anything before PHIs or exception
+      // handling pads.
+      while (InsertPt != BB->end() && (isa<PHINode>(InsertPt) ||
+                                       InsertPt->isEHPad())) {
+        if (isa<CatchSwitchInst>(InsertPt))
+          // A catchswitch cannot have anything in the block except
+          // itself and PHIs.  We'll bail out below.
+          FoundCatchSwitch = true;
+        ++InsertPt;
+      }
     } else {
       InsertPt = TheNeg->getParent()->getParent()->getEntryBlock().begin();
     }
+
+    // We found a catchswitch in the block where we want to move the
+    // neg.  We cannot move anything into that block.  Bail and just
+    // create the neg before BI, as if we hadn't found an existing
+    // neg.
+    if (FoundCatchSwitch)
+      break;
+
     TheNeg->moveBefore(&*InsertPt);
     if (TheNeg->getOpcode() == Instruction::Sub) {
       TheNeg->setHasNoUnsignedWrap(false);

llvm/test/Transforms/Reassociate/reassociate-catchswitch.ll

@@ -0,0 +1,41 @@
+; ModuleID = 'bugpoint-reduced-simplified.bc'
+source_filename = "catchswitch.cpp"
+target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-pc-windows-msvc19.11.0"
+
+define dso_local void @"?f@@YAX_N@Z"(i1 %b) local_unnamed_addr #0 personality i8* bitcast (i32 (...)* @__CxxFrameHandler3 to i8*) {
+entry:
+  br i1 %b, label %if.then, label %if.else
+
+if.then:                                          ; preds = %entry
+  invoke void @"?g@@YAXXZ"()
+          to label %cleanup unwind label %catch.dispatch
+
+if.else:                                          ; preds = %entry
+  invoke void @"?g2@@YAXXZ"()
+          to label %cleanup unwind label %catch.dispatch
+
+catch.dispatch:                                   ; preds = %if.else, %if.then
+  %z.0 = phi i32 [ 3, %if.then ], [ 5, %if.else ]
+  %0 = catchswitch within none [label %catch] unwind to caller
+
+catch:                                            ; preds = %catch.dispatch
+  %1 = catchpad within %0 [i8* null, i32 64, i8* null]
+  %blech = sub nsw i32 5, %z.0
+  %sub = sub nsw i32 %blech, %z.0
+  call void @"?use@@YAXHH@Z"(i32 %z.0, i32 %sub) [ "funclet"(token %1) ]
+  unreachable
+
+cleanup:                                          ; preds = %if.else, %if.then
+  ret void
+}
+
+declare dso_local void @"?g@@YAXXZ"() local_unnamed_addr #0
+
+declare dso_local i32 @__CxxFrameHandler3(...)
+
+declare dso_local void @"?g2@@YAXXZ"() local_unnamed_addr #0
+
+declare dso_local void @"?use@@YAXHH@Z"(i32, i32) local_unnamed_addr #0
+
+attributes #0 = { "use-soft-float"="false" }

llvm/test/Transforms/Reassociate/reassociate-landingpad.ll

@@ -0,0 +1,54 @@
+; Reassociate used to move the negation of $time_1_P14.0 above the
+; landingpad.
+;
+; RUN: opt -reassociate -disable-output < %s
+;
+; ModuleID = 'bugpoint-reduced-simplified.bc'
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+%"lp.2234.4378.7378.12512.15079.17646.20213.22780.25347.27914.40747.53580.74113.76680.86947.89514.92081.94648.115163.130561" = type { i8*, i32 }
+%__type_info.2235.4379.7379.12513.15080.17647.20214.22781.25348.27915.40748.53581.74114.76681.86948.89515.92082.94649.115162.130560 = type { i64*, i8* }
+
+declare i32 @__gxx_personality_v0(...)
+
+declare void @b() #0
+
+define void @a() #0 personality i32 (...)* @__gxx_personality_v0 {
+", bb1":
+  invoke void @b()
+          to label %invoke.cont unwind label %"bb22"
+
+", bb8":                                          ; preds = %invoke.cont
+  invoke void @c()
+          to label %invoke.cont25 unwind label %"bb22"
+
+", bb15":                                         ; preds = %invoke.cont
+  ret void
+
+"bb22":     ; preds = %", bb8", %", bb1"
+  %"$time_1_P14.0" = phi i64 [ undef, %", bb8" ], [ undef, %", bb1" ]
+  %0 = landingpad %"lp.2234.4378.7378.12512.15079.17646.20213.22780.25347.27914.40747.53580.74113.76680.86947.89514.92081.94648.115163.130561"
+          cleanup
+          catch %__type_info.2235.4379.7379.12513.15080.17647.20214.22781.25348.27915.40748.53581.74114.76681.86948.89515.92082.94649.115162.130560* null
+  %r79 = sub i64 0, %"$time_1_P14.0"
+  %r81 = add i64 %r79, undef
+  %r93 = add i64 %r81, undef
+  %r95 = sub i64 %r93, %"$time_1_P14.0"
+  %r98 = icmp ult i64 %r95, undef
+  unreachable
+
+invoke.cont:                                      ; preds = %", bb1"
+  br i1 undef, label %", bb15", label %", bb8"
+
+invoke.cont25:                                    ; preds = %", bb8"
+  unreachable
+}
+
+declare void @c() #0
+
+attributes #0 = { "no-frame-pointer-elim-non-leaf" }
+
+!llvm.module.flags = !{!0}
+
+!0 = !{i32 1, !"Debug Info Version", i32 3}