[llvm] r291603 - [WebAssembly] Only RAUW a constant once in FixFunctionBitcasts

[Derek Schuff via llvm-commits]

Author: dschuff
Date: Tue Jan 10 15:59:53 2017
New Revision: 291603

URL: http://llvm.org/viewvc/llvm-project?rev=291603&view=rev
Log:
[WebAssembly] Only RAUW a constant once in FixFunctionBitcasts

When we collect 2 uses of a function in FindUses and then RAUW when we
visit the first, we end up visiting the wrapper (because the second was
RAUW'd).  We still want to use RAUW instead of just Use->set() because
it has special handling for Constants, so this patch just ensures that
only one use of each constant is added to the work list.

Differential Revision: https://reviews.llvm.org/D28504

Modified:
    llvm/trunk/lib/Target/WebAssembly/WebAssemblyFixFunctionBitcasts.cpp
    llvm/trunk/test/CodeGen/WebAssembly/function-bitcasts.ll

Modified: llvm/trunk/lib/Target/WebAssembly/WebAssemblyFixFunctionBitcasts.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/WebAssembly/WebAssemblyFixFunctionBitcasts.cpp?rev=291603&r1=291602&r2=291603&view=diff
==============================================================================
--- llvm/trunk/lib/Target/WebAssembly/WebAssemblyFixFunctionBitcasts.cpp (original)
+++ llvm/trunk/lib/Target/WebAssembly/WebAssemblyFixFunctionBitcasts.cpp Tue Jan 10 15:59:53 2017
@@ -62,12 +62,19 @@ ModulePass *llvm::createWebAssemblyFixFu
 // Recursively descend the def-use lists from V to find non-bitcast users of
 // bitcasts of V.
 static void FindUses(Value *V, Function &F,
-                     SmallVectorImpl<std::pair<Use *, Function *>> &Uses) {
+                     SmallVectorImpl<std::pair<Use *, Function *>> &Uses,
+                     SmallPtrSetImpl<Constant *> &ConstantBCs) {
   for (Use &U : V->uses()) {
     if (BitCastOperator *BC = dyn_cast<BitCastOperator>(U.getUser()))
-      FindUses(BC, F, Uses);
-    else if (U.get()->getType() != F.getType())
+      FindUses(BC, F, Uses, ConstantBCs);
+    else if (U.get()->getType() != F.getType()) {
+      if (isa<Constant>(U.get())) {
+        // Only add constant bitcasts to the list once; they get RAUW'd
+        auto c = ConstantBCs.insert(cast<Constant>(U.get()));
+        if (!c.second) continue;
+      }
       Uses.push_back(std::make_pair(&U, &F));
+    }
   }
 }
 
@@ -122,10 +129,10 @@ static Function *CreateWrapper(Function
 
 bool FixFunctionBitcasts::runOnModule(Module &M) {
   SmallVector<std::pair<Use *, Function *>, 0> Uses;
+  SmallPtrSet<Constant *, 2> ConstantBCs;
 
   // Collect all the places that need wrappers.
-  for (Function &F : M)
-    FindUses(&F, F, Uses);
+  for (Function &F : M) FindUses(&F, F, Uses, ConstantBCs);
 
   DenseMap<std::pair<Function *, FunctionType *>, Function *> Wrappers;
 

Modified: llvm/trunk/test/CodeGen/WebAssembly/function-bitcasts.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/WebAssembly/function-bitcasts.ll?rev=291603&r1=291602&r2=291603&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/WebAssembly/function-bitcasts.ll (original)
+++ llvm/trunk/test/CodeGen/WebAssembly/function-bitcasts.ll Tue Jan 10 15:59:53 2017
@@ -7,11 +7,18 @@ target triple = "wasm32-unknown-unknown"
 
 ; CHECK-LABEL: test:
 ; CHECK-NEXT: call        .Lbitcast at FUNCTION{{$}}
+; CHECK-NEXT: call        .Lbitcast at FUNCTION{{$}}
 ; CHECK-NEXT: call        .Lbitcast.1 at FUNCTION{{$}}
 ; CHECK-NEXT: i32.const   $push[[L0:[0-9]+]]=, 0
 ; CHECK-NEXT: call        .Lbitcast.2 at FUNCTION, $pop[[L0]]{{$}}
+; CHECK-NEXT: i32.const   $push[[L1:[0-9]+]]=, 0
+; CHECK-NEXT: call        .Lbitcast.2 at FUNCTION, $pop[[L1]]{{$}}
+; CHECK-NEXT: i32.const   $push[[L2:[0-9]+]]=, 0
+; CHECK-NEXT: call        .Lbitcast.2 at FUNCTION, $pop[[L2]]{{$}}
+; CHECK-NEXT: call        foo0 at FUNCTION
 ; CHECK-NEXT: i32.call    $drop=, .Lbitcast.3 at FUNCTION{{$}}
 ; CHECK-NEXT: call        foo2 at FUNCTION{{$}}
+; CHECK-NEXT: call        foo1 at FUNCTION{{$}}
 ; CHECK-NEXT: call        foo3 at FUNCTION{{$}}
 ; CHECK-NEXT: .endfunc
 
@@ -47,10 +54,19 @@ declare void @foo3()
 define void @test() {
 entry:
   call void bitcast (void (i32)* @has_i32_arg to void ()*)()
+  call void bitcast (void (i32)* @has_i32_arg to void ()*)()
   call void bitcast (i32 ()* @has_i32_ret to void ()*)()
   call void bitcast (void ()* @foo0 to void (i32)*)(i32 0)
+  %p = bitcast void ()* @foo0 to void (i32)*
+  call void %p(i32 0)
+  %q = bitcast void ()* @foo0 to void (i32)*
+  call void %q(i32 0)
+  %r = bitcast void (i32)* %q to void ()*
+  call void %r()
   %t = call i32 bitcast (void ()* @foo1 to i32 ()*)()
   call void bitcast (void ()* @foo2 to void ()*)()
+  call void @foo1()
   call void @foo3()
+
   ret void
 }