[SEH] Reimplement x64 SEH using WinEHPrepare

This now emits simple, unoptimized xdata tables for __C_specific_handler
based on the handlers listed in @llvm.eh.actions calls produced by
WinEHPrepare.

This adds support for running __finally blocks when exceptions are
thrown, and removes the old landingpad fan-in codepath.

I ran some manual execution tests on small basic test cases with and
without optimization, as well as on Chrome base_unittests, which uses a
small amount of SEH.  I'm sure there are bugs, and we may need to
revert.

llvm-svn: 235154

1 files changed, 0 insertions, 15 deletions

diff --git a/llvm/lib/CodeGen/WinEHPrepare.cpp b/llvm/lib/CodeGen/WinEHPrepare.cpp
index 35b944ea309..e573f3e7f41 100644
--- a/llvm/lib/CodeGen/WinEHPrepare.cpp
+++ b/llvm/lib/CodeGen/WinEHPrepare.cpp
@@ -306,11 +306,6 @@ FunctionPass *llvm::createWinEHPass(const TargetMachine *TM) {
   return new WinEHPrepare(TM);
 }
 
-// FIXME: Remove this once the backend can handle the prepared IR.
-static cl::opt<bool>
-    SEHPrepare("sehprepare", cl::Hidden,
-               cl::desc("Prepare functions with SEH personalities"));
-
 bool WinEHPrepare::runOnFunction(Function &Fn) {
   SmallVector<LandingPadInst *, 4> LPads;
   SmallVector<ResumeInst *, 4> Resumes;
@@ -334,16 +329,6 @@ bool WinEHPrepare::runOnFunction(Function &Fn) {
 
   DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
 
-  if (isAsynchronousEHPersonality(Personality) && !SEHPrepare) {
-    // Replace all resume instructions with unreachable.
-    // FIXME: Remove this once the backend can handle the prepared IR.
-    for (ResumeInst *Resume : Resumes) {
-      IRBuilder<>(Resume).CreateUnreachable();
-      Resume->eraseFromParent();
-    }
-    return true;
-  }
-
   // If there were any landing pads, prepareExceptionHandlers will make changes.
   prepareExceptionHandlers(Fn, LPads);
   return true;