From 21a466ca4dbdb960b428238b72230caf59205a9e Mon Sep 17 00:00:00 2001
From: Roman Lebedev <lebedev.ri@gmail.com>
Date: Sun, 20 Jun 2021 12:33:57 +0300
Subject: [PATCH] [SimplifyCFG] FoldTwoEntryPHINode(): don't fold if either
 block has it's address taken

Same as with HoistThenElseCodeToIf() (ad87761925c2790aab272138b5bbbde4a93e0383).
---
 lib/Transforms/Utils/SimplifyCFG.cpp          |  5 +++++
 .../CodeGen/AArch64/inlineasm-S-constraint.ll | 14 +++++++++++++
 .../hoist-from-addresstaken-block.ll          | 20 ++++++++++++++++++-
 3 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp
index 4f3559d9779..6c3acb8bbc7 100644
--- a/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -2819,6 +2819,11 @@ static bool FoldTwoEntryPHINode(PHINode *PN, const TargetTransformInfo &TTI,
   }
   assert(DomBlock && "Failed to find root DomBlock");
 
+  // If either of the blocks has it's address taken, we can't do this fold.
+  if ((IfBlock1 && IfBlock1->hasAddressTaken()) ||
+      (IfBlock2 && IfBlock2->hasAddressTaken()))
+    return Changed;
+
   LLVM_DEBUG(dbgs() << "FOUND IF CONDITION!  " << *IfCond
                     << "  T: " << IfTrue->getName()
                     << "  F: " << IfFalse->getName() << "\n");
diff --git a/test/CodeGen/AArch64/inlineasm-S-constraint.ll b/test/CodeGen/AArch64/inlineasm-S-constraint.ll
index 0e1169500e6..16583bb69c0 100644
--- a/test/CodeGen/AArch64/inlineasm-S-constraint.ll
+++ b/test/CodeGen/AArch64/inlineasm-S-constraint.ll
@@ -31,3 +31,17 @@ common.ret:
   %common.retval = phi i32 [ 0, %loc ], [ 42, %loc2 ]
   ret i32 %common.retval
 }
+
+define i32 @test_inline_constraint_S_label_tailmerged2(i1 %in) {
+; CHECK-LABEL: test_inline_constraint_S_label_tailmerged2:
+  call void asm sideeffect "adr x0, $0", "S"(i8* blockaddress(@test_inline_constraint_S_label_tailmerged2, %loc))
+; CHECK: adr x0, .Ltmp{{[0-9]+}}
+  br i1 %in, label %loc, label %loc2
+common.ret:
+  %common.retval = phi i32 [ 0, %loc ], [ 42, %loc2 ]
+  ret i32 %common.retval
+loc:
+  br label %common.ret
+loc2:
+  br label %common.ret
+}
diff --git a/test/Transforms/SimplifyCFG/hoist-from-addresstaken-block.ll b/test/Transforms/SimplifyCFG/hoist-from-addresstaken-block.ll
index d00593e94f9..2fb115504b5 100644
--- a/test/Transforms/SimplifyCFG/hoist-from-addresstaken-block.ll
+++ b/test/Transforms/SimplifyCFG/hoist-from-addresstaken-block.ll
@@ -10,7 +10,7 @@ define i32 @test_inline_constraint_S_label_tailmerged(i1 %in) {
 ; CHECK-NEXT:    ret i32 [[COMMON_RETVAL]]
 ;
   call void asm sideeffect "adr x0, $0", "S"(i8* blockaddress(@test_inline_constraint_S_label_tailmerged, %loc))
-br i1 %in, label %loc, label %loc2
+  br i1 %in, label %loc, label %loc2
 loc:
   br label %common.ret
 loc2:
@@ -19,3 +19,21 @@ common.ret:
   %common.retval = phi i32 [ 0, %loc ], [ 42, %loc2 ]
   ret i32 %common.retval
 }
+
+define i32 @test_inline_constraint_S_label_tailmerged2(i1 %in) {
+; CHECK-LABEL: @test_inline_constraint_S_label_tailmerged2(
+; CHECK-NEXT:  common.ret:
+; CHECK-NEXT:    call void asm sideeffect "adr x0, $0", "S"(i8* blockaddress(@test_inline_constraint_S_label_tailmerged, [[COMMON_RET:%.*]]))
+; CHECK-NEXT:    [[DOT:%.*]] = select i1 [[IN:%.*]], i32 0, i32 42
+; CHECK-NEXT:    ret i32 [[DOT]]
+;
+  call void asm sideeffect "adr x0, $0", "S"(i8* blockaddress(@test_inline_constraint_S_label_tailmerged, %loc))
+  br i1 %in, label %loc, label %loc2
+common.ret:
+  %common.retval = phi i32 [ 0, %loc ], [ 42, %loc2 ]
+  ret i32 %common.retval
+loc:
+  br label %common.ret
+loc2:
+  br label %common.ret
+}