Clean up the handling of inline asm.

Make inline asm a report_fatal_error instead of an assertion failure so
that it's a little friendlier, and add a test to make sure llc -march=js
rejects inline asm.

Also disable the PNaCl inline asm("":::"memory") lowering pass. If people
are using this, it's best that we diagnose it as it likely isn't portable.
There are usually better alternatives.

3 files changed, 18 insertions, 1 deletions

diff --git a/lib/Target/JSBackend/CallHandlers.h b/lib/Target/JSBackend/CallHandlers.h
index eefe491d16..bfdd86571c 100644
--- a/lib/Target/JSBackend/CallHandlers.h
+++ b/lib/Target/JSBackend/CallHandlers.h
@@ -1034,7 +1034,9 @@ void setupCallHandlers() {
 
 std::string handleCall(const Instruction *CI) {
   const Value *CV = getActuallyCalledValue(CI);
-  assert(!isa<InlineAsm>(CV) && "asm() not supported, use EM_ASM() (see emscripten.h)");
+  if (isa<InlineAsm>(CV)) {
+    report_fatal_error("asm() not supported, use EM_ASM() (see emscripten.h)");
+  }
 
   // Get the name to call this function by. If it's a direct call, meaning
   // which know which Function we're calling, avoid calling getValueAsStr, as
diff --git a/lib/Transforms/NaCl/PNaClABISimplify.cpp b/lib/Transforms/NaCl/PNaClABISimplify.cpp
index 4deee01a2b..27dd45e1ea 100644
--- a/lib/Transforms/NaCl/PNaClABISimplify.cpp
+++ b/lib/Transforms/NaCl/PNaClABISimplify.cpp
@@ -138,7 +138,9 @@ void llvm::PNaClABISimplifyAddPostOptPasses(PassManager &PM) {
   // Remove ``asm("":::"memory")``. This must occur after rewriting
   // atomics: a ``fence seq_cst`` surrounded by ``asm("":::"memory")``
   // has special meaning and is translated differently.
+#if 0 // XXX EMSCRIPTEN: asm("":::"memory") does't have special semantics.
   PM.add(createRemoveAsmMemoryPass());
+#endif
 #if 0 // XXX EMSCRIPTEN: PNaCl replaces pointers with ints to simplify their ABI; empscripten doesn't need this.
   // ReplacePtrsWithInts assumes that getelementptr instructions and
   // ConstantExprs have already been expanded out.
diff --git a/test/CodeGen/JS/asm.ll b/test/CodeGen/JS/asm.ll
new file mode 100644
index 0000000000..41a30431da
--- /dev/null
+++ b/test/CodeGen/JS/asm.ll
@@ -0,0 +1,13 @@
+; RUN: not llc -march=js < %s
+
+; Inline asm isn't supported (yet?). llc should report an error when it
+; encounters inline asm.
+;
+; We could support the special case of an empty inline asm string without much
+; work, but code that uses such things most likely isn't portable anyway, and
+; there are usually much better alternatives.
+
+define void @foo() {
+  call void asm "", ""()
+  ret void
+}