[WebAssembly] Fix WebAssemblyOptimizeReturned after r300367

[jgravelle-google]

Summary

Refactoring changed paramHasAttr(1 + i) to paramHasAttr(0), fix that to
paramHasAttr(i).
Add more tests to WebAssemblyOptimizeReturned that catch that
regression.

[rnk]

Oops. I think I confused 'sret' and 'returned' and figured it could only appear on the first argument.

[dschuff]

no worries, I'm always happy for more opportunities to improve our regression tests :D

llvm/trunk/lib/Target/WebAssembly/WebAssemblyOptimizeReturned.cpp

 
 char OptimizeReturned::ID = 0;
 FunctionPass *llvm::createWebAssemblyOptimizeReturned() {
   return new OptimizeReturned();
 }
 
 void OptimizeReturned::visitCallSite(CallSite CS) {
   for (unsigned i = 0, e = CS.getNumArgOperands(); i < e; ++i)
-    if (CS.paramHasAttr(0, Attribute::Returned)) {
+    if (CS.paramHasAttr(i, Attribute::Returned)) {
       Instruction *Inst = CS.getInstruction();
       Value *Arg = CS.getArgOperand(i);
       // Ignore constants, globals, undef, etc.
       if (isa<Constant>(Arg))
         continue;
       // Like replaceDominatedUsesWith but using Instruction/Use dominance.
       for (auto UI = Arg->use_begin(), UE = Arg->use_end(); UI != UE;) {
         Use &U = *UI++;

llvm/trunk/test/CodeGen/WebAssembly/returned.ll

 ; CHECK-NEXT: return{{$}}
 @global = external global i32
 @addr = global i32* @global
 define void @test_constant_arg() {
   %call = call i32* @returns_arg(i32* @global)
   ret void
 }
 declare i32* @returns_arg(i32* returned)
+
+; Test that the optimization isn't performed on arguments without the
+; "returned" attribute.
+
+; CHECK-LABEL: test_other_skipped:
+; CHECK-NEXT: .param   i32, i32, f64{{$}}
+; CHECK-NEXT: {{^}} i32.call     $drop=, do_something@FUNCTION, $0, $1, $2{{$}}
+; CHECK-NEXT: {{^}} call     do_something_with_i32@FUNCTION, $1{{$}}
+; CHECK-NEXT: {{^}} call     do_something_with_double@FUNCTION, $2{{$}}
+declare i32 @do_something(i32 returned, i32, double)
+declare void @do_something_with_i32(i32)
+declare void @do_something_with_double(double)
+define void @test_other_skipped(i32 %a, i32 %b, double %c) {
+    %call = call i32 @do_something(i32 %a, i32 %b, double %c)
+    call void @do_something_with_i32(i32 %b)
+    call void @do_something_with_double(double %c)
+    ret void
+}
+
+; Test that the optimization is performed on arguments other than the first.
+
+; CHECK-LABEL: test_second_arg:
+; CHECK-NEXT: .param   i32, i32{{$}}
+; CHECK-NEXT: .result  i32{{$}}
+; CHECK-NEXT: {{^}} i32.call     $push0=, do_something_else@FUNCTION, $0, $1{{$}}
+; CHECK-NEXT: return   $pop0{{$}}
+declare i32 @do_something_else(i32, i32 returned)
+define i32 @test_second_arg(i32 %a, i32 %b) {
+    %call = call i32 @do_something_else(i32 %a, i32 %b)
+    ret i32 %b
+}