[WebAssembly] Don't write SP back when prolog is generated only for EH
Summary:
When we don't actually have stack-allocated variables but need SP only
to support EH, we don't need to write SP back in the epilog, because we
don't bump down the stack pointer.
Reviewers: dschuff
Subscribers: jgravelle-google, sbc100, sunfish, llvm-commits
Differential Revision: https://reviews.llvm.org/D51114
llvm-svn: 340454
diff --git a/llvm/test/CodeGen/WebAssembly/exception.ll b/llvm/test/CodeGen/WebAssembly/exception.ll
index a0256d2..0757f97 100644
--- a/llvm/test/CodeGen/WebAssembly/exception.ll
+++ b/llvm/test/CodeGen/WebAssembly/exception.ll
@@ -217,6 +217,35 @@
cleanupret from %8 unwind to caller
}
+; When a function does not have stack-allocated objects, it does not need to
+; store SP back to __stack_pointer global at the epilog.
+
+; CHECK-LABEL: no_sp_writeback
+; CHECK: try
+; CHECK: call foo@FUNCTION
+; CHECK: end_try
+; CHECK-NOT: set_global __stack_pointer@GLOBAL
+; CHECK: return
+define void @no_sp_writeback() personality i8* bitcast (i32 (...)* @__gxx_wasm_personality_v0 to i8*) {
+entry:
+ invoke void @foo()
+ to label %try.cont unwind label %catch.dispatch
+
+catch.dispatch: ; preds = %entry
+ %0 = catchswitch within none [label %catch.start] unwind to caller
+
+catch.start: ; preds = %catch.dispatch
+ %1 = catchpad within %0 [i8* null]
+ %2 = call i8* @llvm.wasm.get.exception(token %1)
+ %3 = call i32 @llvm.wasm.get.ehselector(token %1)
+ %4 = call i8* @__cxa_begin_catch(i8* %2) #2 [ "funclet"(token %1) ]
+ call void @__cxa_end_catch() [ "funclet"(token %1) ]
+ catchret from %1 to label %try.cont
+
+try.cont: ; preds = %entry, %catch.start
+ ret void
+}
+
declare void @foo()
declare void @bar(i32*)
declare i32 @__gxx_wasm_personality_v0(...)