[llvm] r241509 - [WinEH] Insert the EH code load before the block terminator

[Reid Kleckner]

Author: rnk
Date: Mon Jul  6 16:13:43 2015
New Revision: 241509

URL: http://llvm.org/viewvc/llvm-project?rev=241509&view=rev
Log:
[WinEH] Insert the EH code load before the block terminator

The previous code put the load after the terminator, leading to invalid
IR and downstream crashes. This caused http://crbug.com/506446.

Added:
    llvm/trunk/test/CodeGen/WinEH/seh-exception-code.ll
Modified:
    llvm/trunk/lib/CodeGen/WinEHPrepare.cpp

Modified: llvm/trunk/lib/CodeGen/WinEHPrepare.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/WinEHPrepare.cpp?rev=241509&r1=241508&r2=241509&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/WinEHPrepare.cpp (original)
+++ llvm/trunk/lib/CodeGen/WinEHPrepare.cpp Mon Jul  6 16:13:43 2015
@@ -833,7 +833,7 @@ bool WinEHPrepare::prepareExceptionHandl
         LoadInst *LI;
         if (auto *Phi = dyn_cast<PHINode>(I))
           LI = new LoadInst(SEHExceptionCodeSlot, "sehcode", false,
-                            Phi->getIncomingBlock(*U));
+                            Phi->getIncomingBlock(*U)->getTerminator());
         else
           LI = new LoadInst(SEHExceptionCodeSlot, "sehcode", false, I);
         U->set(LI);

Added: llvm/trunk/test/CodeGen/WinEH/seh-exception-code.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/WinEH/seh-exception-code.ll?rev=241509&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/WinEH/seh-exception-code.ll (added)
+++ llvm/trunk/test/CodeGen/WinEH/seh-exception-code.ll Mon Jul  6 16:13:43 2015
@@ -0,0 +1,66 @@
+; RUN: opt -winehprepare -S < %s | FileCheck %s
+
+; WinEHPrepare was crashing during phi demotion.
+
+target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-pc-windows-msvc18.0.0"
+
+declare i32 @__C_specific_handler(...)
+
+ at str = linkonce_odr unnamed_addr constant [16 x i8] c"caught it! %lx\0A\00", align 1
+
+; Function Attrs: nounwind uwtable
+declare void @maycrash()
+
+; Function Attrs: nounwind
+declare i32 @printf(i8* nocapture readonly, ...)
+
+; Function Attrs: nounwind uwtable
+define void @doit() personality i8* bitcast (i32 (...)* @__C_specific_handler to i8*) {
+entry:
+  invoke void @maycrash()
+          to label %invoke.cont unwind label %lpad
+
+invoke.cont:                                      ; preds = %entry
+  invoke void @maycrash()
+          to label %__try.cont unwind label %lpad.1
+
+lpad:                                             ; preds = %entry
+  %0 = landingpad { i8*, i32 }
+          catch i8* null
+  %1 = extractvalue { i8*, i32 } %0, 0
+  br label %__except
+
+lpad.1:                                           ; preds = %invoke.cont, %lpad
+  %2 = landingpad { i8*, i32 }
+          catch i8* null
+  %3 = extractvalue { i8*, i32 } %2, 0
+  br label %__except
+
+__except:                                         ; preds = %lpad, %lpad.1
+  %exn.slot.0 = phi i8* [ %3, %lpad.1 ], [ %1, %lpad ]
+  %4 = ptrtoint i8* %exn.slot.0 to i64
+  %5 = trunc i64 %4 to i32
+  %call = tail call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([16 x i8], [16 x i8]* @str, i64 0, i64 0), i32 %5)
+  br label %__try.cont
+
+__try.cont:                                       ; preds = %invoke.cont, %__except
+  ret void
+}
+
+; CHECK-LABEL: define void @doit()
+; CHECK: landingpad
+; CHECK: indirectbr i8* %{{[^,]*}}, [label %[[except_split1:.*]]]
+; CHECK: [[except_split1]]:
+; CHECK: call i32 @llvm.eh.exceptioncode()
+; CHECK: br label %__except
+;
+; CHECK: landingpad
+; CHECK: indirectbr i8* %{{[^,]*}}, [label %[[except_split2:.*]]]
+; CHECK: [[except_split2]]:
+; CHECK: call i32 @llvm.eh.exceptioncode()
+; CHECK: br label %__except
+;
+; CHECK: __except:
+; CHECK: phi
+; CHECK: call i32 (i8*, ...) @printf