Re-land "[WinEH] Add an EH registration and state insertion pass for 32-bit x86"

This reverts commit r236360.

This change exposed a bug in WinEHPrepare by opting win32 code into EH
preparation. We already knew that WinEHPrepare has bugs, and is the
status quo for x64, so I don't think that's a reason to hold off on this
change. I disabled exceptions in the sanitizer tests in r236505 and an
earlier revision.

llvm-svn: 236508

1 files changed, 6 insertions, 5 deletions

diff --git a/llvm/lib/CodeGen/WinEHPrepare.cpp b/llvm/lib/CodeGen/WinEHPrepare.cpp
index c1067c5d560..db91c02ee46 100644
--- a/llvm/lib/CodeGen/WinEHPrepare.cpp
+++ b/llvm/lib/CodeGen/WinEHPrepare.cpp
@@ -8,9 +8,11 @@
 //===----------------------------------------------------------------------===//
 //
 // This pass lowers LLVM IR exception handling into something closer to what the
-// backend wants. It snifs the personality function to see which kind of
-// preparation is necessary. If the personality function uses the Itanium LSDA,
-// this pass delegates to the DWARF EH preparation pass.
+// backend wants for functions using a personality function from a runtime
+// provided by MSVC. Functions with other personality functions are left alone
+// and may be prepared by other passes. In particular, all supported MSVC
+// personality functions require cleanup code to be outlined, and the C++
+// personality requires catch handler code to be outlined.
 //
 //===----------------------------------------------------------------------===//
 
@@ -31,7 +33,6 @@
 #include "llvm/IR/Module.h"
 #include "llvm/IR/PatternMatch.h"
 #include "llvm/Pass.h"
-#include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
@@ -922,7 +923,7 @@ bool WinEHPrepare::prepareExceptionHandlers(
   if (SEHExceptionCodeSlot) {
     if (SEHExceptionCodeSlot->hasNUses(0))
       SEHExceptionCodeSlot->eraseFromParent();
-    else
+    else if (isAllocaPromotable(SEHExceptionCodeSlot))
       PromoteMemToReg(SEHExceptionCodeSlot, *DT);
   }