[llvm] f5cff29 - [WebAssembly] Fix PHI when relaying longjmps
Heejin Ahn via llvm-commits
llvm-commits at lists.llvm.org
Thu Aug 26 17:25:52 PDT 2021
Author: Heejin Ahn
Date: 2021-08-26T17:25:26-07:00
New Revision: f5cff292e297ad5094f35d6223a199e389adcd99
URL: https://github.com/llvm/llvm-project/commit/f5cff292e297ad5094f35d6223a199e389adcd99
DIFF: https://github.com/llvm/llvm-project/commit/f5cff292e297ad5094f35d6223a199e389adcd99.diff
LOG: [WebAssembly] Fix PHI when relaying longjmps
When doing Emscritpen EH, if SjLj is also enabled and used and if the
thrown exception has a possiblity being a longjmp instead of an
exception, we shouldn't swallow it; we should rethrow, or relay it. It
was done in D106525 and the code is here:
https://github.com/llvm/llvm-project/blob/8441a8eea8007b9eaaaabf76055949180a702d6d/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp#L858-L898
Here is the pseudocode of that part: (copied from comments)
```
if (%__THREW__.val == 0 || %__THREW__.val == 1)
goto %tail
else
goto %longjmp.rethrow
longjmp.rethrow: ;; This is longjmp. Rethrow it
%__threwValue.val = __threwValue
emscripten_longjmp(%__THREW__.val, %__threwValue.val);
tail: ;; Nothing happened or an exception is thrown
... Continue exception handling ...
```
If the current BB (where the `invoke` is created) has successors that
has the current BB as its PHI incoming node, now that has to change to
`tail` in the pseudocode, because `tail` is the latest BB that is
connected with the next BB, but this was missing.
Reviewed By: tlively
Differential Revision: https://reviews.llvm.org/D108785
Added:
Modified:
llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
llvm/test/CodeGen/WebAssembly/lower-em-ehsjlj.ll
Removed:
################################################################################
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
index db6aa0caaa47..110f5239b34c 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
@@ -891,6 +891,7 @@ bool WebAssemblyLowerEmscriptenEHSjLj::runEHOnFunction(Function &F) {
IRB.CreateUnreachable();
IRB.SetInsertPoint(Tail);
+ BB.replaceSuccessorsPhiUsesWith(&BB, Tail);
}
// Insert a branch based on __THREW__ variable
diff --git a/llvm/test/CodeGen/WebAssembly/lower-em-ehsjlj.ll b/llvm/test/CodeGen/WebAssembly/lower-em-ehsjlj.ll
index fd0c9445ba8d..9d6ece6525f0 100644
--- a/llvm/test/CodeGen/WebAssembly/lower-em-ehsjlj.ll
+++ b/llvm/test/CodeGen/WebAssembly/lower-em-ehsjlj.ll
@@ -65,6 +65,10 @@ entry:
; CHECK-NEXT: %or = or i1 %cmp.eq.zero, %cmp.eq.one
; CHECK-NEXT: br i1 %or, label %tail, label %longjmp.rethrow
+; CHECK: try.cont:
+; CHECK-NEXT: %phi = phi i32 [ undef, %tail ], [ undef, %lpad ]
+; CHECK-NEXT: ret void
+
; CHECK: tail:
; CHECK-NEXT: %cmp = icmp eq i32 %__THREW__.val, 1
; CHECK-NEXT: br i1 %cmp, label %lpad, label %try.cont
@@ -84,6 +88,7 @@ lpad: ; preds = %entry
br label %try.cont
try.cont: ; preds = %entry, %lpad
+ %phi = phi i32 [ undef, %entry ], [ undef, %lpad ]
ret void
}
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