[WebAssembly] Restore __stack_pointer after catch instructions

Summary:
After the stack is unwound due to a thrown exception, the
`__stack_pointer` global can point to an invalid address. This inserts
instructions that restore `__stack_pointer` global.

Reviewers: jgravelle-google, dschuff

Subscribers: mgorny, sbc100, sunfish, llvm-commits

Differential Revision: https://reviews.llvm.org/D50980

llvm-svn: 340339

1 files changed, 4 insertions, 0 deletions

diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
index 7c10f022cbb..1cc688599a9 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
@@ -58,6 +58,7 @@ extern "C" void LLVMInitializeWebAssemblyTarget() {
   initializeOptimizeReturnedPass(PR);
   initializeWebAssemblyArgumentMovePass(PR);
   initializeWebAssemblySetP2AlignOperandsPass(PR);
+  initializeWebAssemblyEHRestoreStackPointerPass(PR);
   initializeWebAssemblyReplacePhysRegsPass(PR);
   initializeWebAssemblyPrepareForLiveIntervalsPass(PR);
   initializeWebAssemblyOptimizeLiveIntervalsPass(PR);
@@ -280,6 +281,9 @@ void WebAssemblyPassConfig::addPostRegAlloc() {
 void WebAssemblyPassConfig::addPreEmitPass() {
   TargetPassConfig::addPreEmitPass();
 
+  // Restore __stack_pointer global after an exception is thrown.
+  addPass(createWebAssemblyEHRestoreStackPointer());
+
   // Now that we have a prologue and epilogue and all frame indices are
   // rewritten, eliminate SP and FP. This allows them to be stackified,
   // colored, and numbered with the rest of the registers.