[llvm] 3c1476d - [IPSCCP] Drop argmemonly after replacing pointer argument.

[Florian Hahn via llvm-commits]

Author: Florian Hahn
Date: 2020-07-25T11:52:14+01:00
New Revision: 3c1476d26c769cd97a631a129b30c62232ac96b6

URL: https://github.com/llvm/llvm-project/commit/3c1476d26c769cd97a631a129b30c62232ac96b6
DIFF: https://github.com/llvm/llvm-project/commit/3c1476d26c769cd97a631a129b30c62232ac96b6.diff

LOG: [IPSCCP] Drop argmemonly after replacing pointer argument.

This patch updates IPSCCP to drop argmemonly and
inaccessiblemem_or_argmemonly if it replaces a pointer argument.

Fixes PR46717.

Reviewers: efriedma, davide, nikic, jdoerfert

Reviewed By: efriedma, jdoerfert

Differential Revision: https://reviews.llvm.org/D84432

Added: 
    

Modified: 
    llvm/lib/Transforms/Scalar/SCCP.cpp
    llvm/test/Transforms/SCCP/ipscp-drop-argmemonly.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Scalar/SCCP.cpp b/llvm/lib/Transforms/Scalar/SCCP.cpp
index 32dc14e5ec19..428f9675e088 100644
--- a/llvm/lib/Transforms/Scalar/SCCP.cpp
+++ b/llvm/lib/Transforms/Scalar/SCCP.cpp
@@ -1911,15 +1911,35 @@ bool llvm::runIPSCCP(
 
     SmallVector<BasicBlock *, 512> BlocksToErase;
 
-    if (Solver.isBlockExecutable(&F.front()))
-      for (Function::arg_iterator AI = F.arg_begin(), E = F.arg_end(); AI != E;
-           ++AI) {
-        if (!AI->use_empty() && tryToReplaceWithConstant(Solver, &*AI)) {
+    if (Solver.isBlockExecutable(&F.front())) {
+      bool ReplacedPointerArg = false;
+      for (Argument &Arg : F.args()) {
+        if (!Arg.use_empty() && tryToReplaceWithConstant(Solver, &Arg)) {
+          ReplacedPointerArg |= Arg.getType()->isPointerTy();
           ++IPNumArgsElimed;
-          continue;
         }
       }
 
+      // If we replaced an argument, the argmemonly and
+      // inaccessiblemem_or_argmemonly attributes do not hold any longer. Remove
+      // them from both the function and callsites.
+      if (ReplacedPointerArg) {
+        SmallVector<Attribute::AttrKind, 2> AttributesToRemove = {
+            Attribute::ArgMemOnly, Attribute::InaccessibleMemOrArgMemOnly};
+        for (auto Attr : AttributesToRemove)
+          F.removeFnAttr(Attr);
+
+        for (User *U : F.users()) {
+          auto *CB = dyn_cast<CallBase>(U);
+          if (!CB || CB->getCalledFunction() != &F)
+            continue;
+
+          for (auto Attr : AttributesToRemove)
+            CB->removeAttribute(AttributeList::FunctionIndex, Attr);
+        }
+      }
+    }
+
     SmallPtrSet<Value *, 32> InsertedValues;
     for (BasicBlock &BB : F) {
       if (!Solver.isBlockExecutable(&BB)) {

diff  --git a/llvm/test/Transforms/SCCP/ipscp-drop-argmemonly.ll b/llvm/test/Transforms/SCCP/ipscp-drop-argmemonly.ll
index a110476eb430..2e3a35779a15 100644
--- a/llvm/test/Transforms/SCCP/ipscp-drop-argmemonly.ll
+++ b/llvm/test/Transforms/SCCP/ipscp-drop-argmemonly.ll
@@ -11,7 +11,7 @@
 ; Here the pointer argument %arg will be replaced by a constant. We need to
 ; drop argmemonly.
 define internal void @ptrarg.1(i32* %arg, i32 %val) argmemonly nounwind {
-; CHECK: Function Attrs: argmemonly nounwind
+; CHECK: Function Attrs: nounwind
 ; CHECK-LABEL: @ptrarg.1(
 ; CHECK-NEXT:    store i32 10, i32* @g, align 4
 ; CHECK-NEXT:    ret void
@@ -59,7 +59,7 @@ define void @caller.2(i32* %ptr) {
 ; Here the pointer argument %arg will be replaced by a constant. We need to
 ; drop inaccessiblemem_or_argmemonly.
 define internal void @ptrarg.3(i32* %arg, i32 %val) inaccessiblemem_or_argmemonly nounwind {
-; CHECK: Function Attrs: inaccessiblemem_or_argmemonly nounwind
+; CHECK: Function Attrs: nounwind
 ; CHECK-LABEL: @ptrarg.3(
 ; CHECK-NEXT:    store i32 10, i32* @g, align 4
 ; CHECK-NEXT:    ret void
@@ -107,7 +107,7 @@ define void @caller.4(i32* %ptr) {
 ; Here the pointer argument %arg will be replaced by a constant. We need to
 ; drop inaccessiblemem_or_argmemonly.
 define internal void @ptrarg.5(i32* %arg, i32 %val) argmemonly inaccessiblemem_or_argmemonly nounwind {
-; CHECK: Function Attrs: argmemonly inaccessiblemem_or_argmemonly nounwind
+; CHECK: Function Attrs: nounwind
 ; CHECK-LABEL: @ptrarg.5(
 ; CHECK-NEXT:    store i32 10, i32* @g, align 4
 ; CHECK-NEXT:    ret void
@@ -143,9 +143,9 @@ define internal void @ptrarg.6.cs.attributes(i32* %arg, i32 %val) {
 define i32 @caller.6.cs.attributes(i32 %n) {
 ; CHECK-LABEL: @caller.6.cs.attributes(
 ; CHECK-NEXT:    store i32 1, i32* @g, align 4
-; CHECK-NEXT:    tail call void @ptrarg.5(i32* @g, i32 10) [[ARGMEMONLY_INACCESSIBLEMEM_OR_ARGMEMONLY_NOUNWIND:#[0-9]+]]
-; CHECK-NEXT:    tail call void @ptrarg.5(i32* @g, i32 10) [[INACCESSIBLEMEM_OR_ARGMEMONLY_NOUNWIND:#[0-9]+]]
-; CHECK-NEXT:    tail call void @ptrarg.5(i32* @g, i32 10) [[ARGMEMONLY_NOUNWIND:#[0-9]+]]
+; CHECK-NEXT:    tail call void @ptrarg.5(i32* @g, i32 10) [[NOUNWIND:#[0-9]+]]
+; CHECK-NEXT:    tail call void @ptrarg.5(i32* @g, i32 10) [[NOUNWIND:#[0-9]+]]
+; CHECK-NEXT:    tail call void @ptrarg.5(i32* @g, i32 10) [[NOUNWIND:#[0-9]+]]
 ; CHECK-NEXT:    tail call void @ptrarg.5(i32* @g, i32 10) [[NOUNWIND:#[0-9]+]]
 ; CHECK-NEXT:    [[G_VAL:%.*]] = load i32, i32* @g, align 4
 ; CHECK-NEXT:    ret i32 [[G_VAL]]
@@ -159,7 +159,4 @@ define i32 @caller.6.cs.attributes(i32 %n) {
   ret i32 %g.val
 }
 
-; CHECK-DAG: [[ARGMEMONLY_INACCESSIBLEMEM_OR_ARGMEMONLY_NOUNWIND]] = { argmemonly inaccessiblemem_or_argmemonly nounwind }
-; CHECK-DAG: [[INACCESSIBLEMEM_OR_ARGMEMONLY_NOUNWIND]] = { inaccessiblemem_or_argmemonly nounwind }
-; CHECK-DAG: [[ARGMEMONLY_NOUNWIND]] = { argmemonly nounwind }
-; CHECK-DAG: [[NOUNWIND]] = { nounwind }
+; CHECK: [[NOUNWIND]] = { nounwind }