[MoveAutoInit] Ignore unreachable basicblocks and handle catchswitch (#78232)

Fixes #78049
This patch has done:
- Ignore unreachable predecessors when looking for nearest common
dominator.
- Check catchswitch with `getFirstNonPHI`, instead of
`getFirstInsertionPt`. The latter skips EHPad.

Author: XChy

llvm/lib/Transforms/Utils/MoveAutoInit.cpp

@@ -164,6 +164,9 @@ static bool runMoveAutoInit(Function &F, DominatorTree &DT, MemorySSA &MSSA) {
         if (TransitiveSuccessors.count(Pred))
           continue;
 
+        if (!DT.isReachableFromEntry(Pred))
+          continue;
+
         DominatingPredecessor =
             DominatingPredecessor
                 ? DT.findNearestCommonDominator(DominatingPredecessor, Pred)
@@ -178,9 +181,10 @@ static bool runMoveAutoInit(Function &F, DominatorTree &DT, MemorySSA &MSSA) {
 
     // CatchSwitchInst blocks can only have one instruction, so they are not
     // good candidates for insertion.
-    while (isa<CatchSwitchInst>(UsersDominator->getFirstInsertionPt())) {
+    while (isa<CatchSwitchInst>(UsersDominator->getFirstNonPHI())) {
       for (BasicBlock *Pred : predecessors(UsersDominator))
-        UsersDominator = DT.findNearestCommonDominator(UsersDominator, Pred);
+        if (DT.isReachableFromEntry(Pred))
+          UsersDominator = DT.findNearestCommonDominator(UsersDominator, Pred);
     }
 
     // We finally found a place where I can be moved while not introducing extra

llvm/test/Transforms/MoveAutoInit/catchswitch.ll

@@ -0,0 +1,57 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4
+; RUN: opt < %s -S -passes='move-auto-init' -verify-memoryssa | FileCheck %s
+
+declare void @dummy()
+declare void @dummy1()
+
+define void @test() personality ptr @dummy {
+; CHECK-LABEL: define void @test() personality ptr @dummy {
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[P:%.*]] = alloca [2 x i16], i32 0, align 2
+; CHECK-NEXT:    br label [[MIDDLE:%.*]]
+; CHECK:       middle:
+; CHECK-NEXT:    store i32 0, ptr [[P]], align 2, !annotation [[META0:![0-9]+]]
+; CHECK-NEXT:    [[CALL:%.*]] = invoke ptr @dummy()
+; CHECK-NEXT:            to label [[CLEAN:%.*]] unwind label [[CATCHBB:%.*]]
+; CHECK:       clean:
+; CHECK-NEXT:    ret void
+; CHECK:       catchbb:
+; CHECK-NEXT:    [[CS:%.*]] = catchswitch within none [label [[PAD:%.*]], label %pad1] unwind to caller
+; CHECK:       pad:
+; CHECK-NEXT:    [[C:%.*]] = catchpad within [[CS]] [i32 0]
+; CHECK-NEXT:    call void @dummy1()
+; CHECK-NEXT:    ret void
+; CHECK:       pad1:
+; CHECK-NEXT:    [[C1:%.*]] = catchpad within [[CS]] [i32 0]
+; CHECK-NEXT:    call void @dummy1()
+; CHECK-NEXT:    ret void
+;
+entry:
+  %p = alloca [2 x i16], i32 0, align 2
+  store i32 0, ptr %p, align 2, !annotation !0
+  br label %middle
+
+middle:
+  %call = invoke ptr @dummy() to label %clean unwind label %catchbb
+
+clean:
+  ret void
+
+catchbb:
+  %cs = catchswitch within none [label %pad, label %pad1] unwind to caller
+
+pad:
+  %c = catchpad within %cs [i32 0]
+  call void @dummy1()
+  ret void
+
+pad1:
+  %c1 = catchpad within %cs [i32 0]
+  call void @dummy1()
+  ret void
+}
+
+!0 = !{!"auto-init"}
+;.
+; CHECK: [[META0]] = !{!"auto-init"}
+;.

llvm/test/Transforms/MoveAutoInit/loop.ll

@@ -7,7 +7,7 @@ define void @foo(i32 %x) {
 ; CHECK-LABEL: @foo(
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    [[BUFFER:%.*]] = alloca [80 x i32], align 16
-; CHECK-NEXT:    call void @llvm.memset.p0.i64(ptr align 16 [[BUFFER]], i8 -86, i64 320, i1 false), !annotation !0
+; CHECK-NEXT:    call void @llvm.memset.p0.i64(ptr align 16 [[BUFFER]], i8 -86, i64 320, i1 false), !annotation [[META0:![0-9]+]]
 ; CHECK-NEXT:    br label [[DO_BODY:%.*]]
 ; CHECK:       do.body:
 ; CHECK-NEXT:    [[X_ADDR_0:%.*]] = phi i32 [ [[X:%.*]], [[ENTRY:%.*]] ], [ [[DEC:%.*]], [[DO_COND:%.*]] ]
@@ -53,7 +53,7 @@ define void @bar(i32 %x, i32 %y) {
 ; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp ne i32 [[Y:%.*]], 0
 ; CHECK-NEXT:    br i1 [[TOBOOL]], label [[IF_THEN:%.*]], label [[IF_END:%.*]]
 ; CHECK:       if.then:
-; CHECK-NEXT:    call void @llvm.memset.p0.i64(ptr align 16 [[BUFFER]], i8 -86, i64 320, i1 false), !annotation !0
+; CHECK-NEXT:    call void @llvm.memset.p0.i64(ptr align 16 [[BUFFER]], i8 -86, i64 320, i1 false), !annotation [[META0]]
 ; CHECK-NEXT:    [[ADD:%.*]] = add nsw i32 [[X:%.*]], [[Y]]
 ; CHECK-NEXT:    br label [[DO_BODY:%.*]]
 ; CHECK:       do.body:
@@ -99,4 +99,43 @@ if.end:                                           ; preds = %do.end, %entry
   ret void
 }
 
+declare void @dummy()
+
+define void @unreachable_pred() {
+; CHECK-LABEL: @unreachable_pred(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[P:%.*]] = alloca [2 x i16], i32 0, align 2
+; CHECK-NEXT:    store i32 0, ptr [[P]], align 2, !annotation [[META0]]
+; CHECK-NEXT:    br i1 true, label [[LOOP:%.*]], label [[USEBB:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    call void @dummy()
+; CHECK-NEXT:    br label [[LOOP]]
+; CHECK:       a:
+; CHECK-NEXT:    br label [[LOOP]]
+; CHECK:       b:
+; CHECK-NEXT:    br label [[LOOP]]
+; CHECK:       usebb:
+; CHECK-NEXT:    [[USE_P:%.*]] = icmp ult ptr null, [[P]]
+; CHECK-NEXT:    ret void
+;
+entry:
+  %p = alloca [2 x i16], i32 0, align 2
+  store i32 0, ptr %p, align 2, !annotation !0
+  br i1 true, label %loop, label %usebb
+
+loop:
+  call void @dummy()
+  br label %loop
+
+a:
+  br label %loop
+
+b:
+  br label %loop
+
+usebb:
+  %use_p = icmp ult ptr null, %p
+  ret void
+}
+
 !0 = !{!"auto-init"}