From 3183c50ddf678f87a05db0c59129f77db11a3be6 Mon Sep 17 00:00:00 2001
From: Reid Kleckner <reid@kleckner.net>
Date: Thu, 16 Apr 2015 00:02:04 +0000
Subject: [PATCH] [SEH] Deal with users of the old lpad for SEH catch-all
 blocks

The way we split SEH catch-all blocks can leave some dead EH values
behind at -O0. Try to remove them, and if we fail, replace them all with
undef.

Fixes a crash when removing the old unreachable landingpad which is
still used by extractvalue instructions in the catch-all block.

llvm-svn: 235061
---
 lib/CodeGen/WinEHPrepare.cpp        |  9 +++++
 test/CodeGen/WinEH/seh-catch-all.ll | 59 +++++++++++++++++++++++++++++
 2 files changed, 68 insertions(+)
 create mode 100644 test/CodeGen/WinEH/seh-catch-all.ll

diff --git a/lib/CodeGen/WinEHPrepare.cpp b/lib/CodeGen/WinEHPrepare.cpp
index afe26ff8224..4b0ce21111b 100644
--- a/lib/CodeGen/WinEHPrepare.cpp
+++ b/lib/CodeGen/WinEHPrepare.cpp
@@ -433,6 +433,10 @@ bool WinEHPrepare::prepareExceptionHandlers(
       Invoke->setUnwindDest(NewLPadBB);
     }
 
+    // If anyone is still using the old landingpad value, just give them undef
+    // instead. The eh pointer and selector values are not real.
+    LPad->replaceAllUsesWith(UndefValue::get(LPad->getType()));
+
     // Replace the mapping of any nested landing pad that previously mapped
     // to this landing pad with a referenced to the cloned version.
     for (auto &LPadPair : NestedLPtoOriginalLP) {
@@ -636,6 +640,11 @@ void WinEHPrepare::promoteLandingPadValues(LandingPadInst *LPad) {
     PromoteMemToReg(EHAllocas, *DT);
     EHAllocas.clear();
   }
+
+  // After promotion, some extracts may be trivially dead. Remove them.
+  SmallVector<Value *, 4> Users(LPad->user_begin(), LPad->user_end());
+  for (auto *U : Users)
+    RecursivelyDeleteTriviallyDeadInstructions(U);
 }
 
 void WinEHPrepare::completeNestedLandingPad(Function *ParentFn,
diff --git a/test/CodeGen/WinEH/seh-catch-all.ll b/test/CodeGen/WinEH/seh-catch-all.ll
new file mode 100644
index 00000000000..bbe3443fa2c
--- /dev/null
+++ b/test/CodeGen/WinEH/seh-catch-all.ll
@@ -0,0 +1,59 @@
+; RUN: opt -S -winehprepare -sehprepare < %s | FileCheck %s
+
+target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-pc-windows-msvc"
+
+@str.__except = internal unnamed_addr constant [9 x i8] c"__except\00", align 1
+
+; Function Attrs: uwtable
+
+declare i32 @puts(i8*)
+
+define void @may_crash() {
+entry:
+  store volatile i32 42, i32* null, align 4
+  ret void
+}
+
+declare i32 @__C_specific_handler(...)
+
+; Function Attrs: nounwind readnone
+declare i8* @llvm.frameaddress(i32)
+
+; Function Attrs: uwtable
+define void @seh_catch_all() {
+entry:
+  %exn.slot = alloca i8*
+  %ehselector.slot = alloca i32
+  invoke void @may_crash()
+          to label %invoke.cont unwind label %lpad
+
+invoke.cont:                                      ; preds = %entry
+  br label %__try.cont
+
+lpad:                                             ; preds = %entry
+  %0 = landingpad { i8*, i32 } personality i8* bitcast (i32 (...)* @__C_specific_handler to i8*)
+          catch i8* null
+  %1 = extractvalue { i8*, i32 } %0, 0
+  store i8* %1, i8** %exn.slot
+  %2 = extractvalue { i8*, i32 } %0, 1
+  store i32 %2, i32* %ehselector.slot
+  br label %__except
+
+__except:                                         ; preds = %lpad
+  %call = call i32 @puts(i8* getelementptr inbounds ([9 x i8], [9 x i8]* @str.__except, i32 0, i32 0))
+  br label %__try.cont
+
+__try.cont:                                       ; preds = %__except, %invoke.cont
+  ret void
+}
+
+; CHECK-LABEL: define void @seh_catch_all()
+; CHECK: landingpad
+; CHECK-NEXT: catch i8* null
+; CHECK-NEXT: call i8* (...)* @llvm.eh.actions(i32 1, i8* null, i32 -1, i8* blockaddress(@seh_catch_all, %catch.all))
+; CHECK-NEXT: indirectbr
+;
+; CHECK: catch.all:
+; CHECK-NOT: extractvalue
+; CHECK: call i32 @puts