[PATCH] D69312: [FPEnv] Teach the IRBuilder about correct use of the strictfp attribute.

[Kevin P. Neal via Phabricator via llvm-commits]

kpn created this revision.
kpn added reviewers: spatel, rsmith, rjmccall, andrew.w.kaylor.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.

The IRBuilder needs to add the strictfp attribute to function definitions and calls when constrained floating point is enabled.

Since so far all front ends have had to do is flip the constrained switch, I've made this patch always add the required attributes when said constrained switch is enabled. This continues to keep changes to front ends minimal.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D69312

Files:
  llvm/include/llvm/IR/IRBuilder.h
  llvm/unittests/IR/IRBuilderTest.cpp


Index: llvm/unittests/IR/IRBuilderTest.cpp
===================================================================
--- llvm/unittests/IR/IRBuilderTest.cpp
+++ llvm/unittests/IR/IRBuilderTest.cpp
@@ -229,6 +229,15 @@
   II = cast<IntrinsicInst>(VDouble);
   EXPECT_EQ(II->getIntrinsicID(), Intrinsic::experimental_constrained_fpext);
 
+  // Verify attributes on the call are created automatically.
+  AttributeSet CallAttrs = II->getAttributes().getFnAttributes();
+  EXPECT_EQ(CallAttrs.hasAttribute(Attribute::StrictFP), true);
+
+  // Verify attributes on the containing function are created automatically.
+  AttributeList Attrs = BB->getParent()->getAttributes();
+  AttributeSet FnAttrs = Attrs.getFnAttributes();
+  EXPECT_EQ(FnAttrs.hasAttribute(Attribute::StrictFP), true);
+
   // Verify the codepaths for setting and overriding the default metadata.
   V = Builder.CreateFAdd(V, V);
   ASSERT_TRUE(isa<ConstrainedFPIntrinsic>(V));
Index: llvm/include/llvm/IR/IRBuilder.h
===================================================================
--- llvm/include/llvm/IR/IRBuilder.h
+++ llvm/include/llvm/IR/IRBuilder.h
@@ -255,6 +255,21 @@
     return DefaultConstrainedRounding;
   }
 
+  void setConstrainedFPFunctionAttr() {
+    assert(BB && "Must have a basic block to set any function attributes!");
+
+    Function *F = BB->getParent();
+    if (!F->hasFnAttribute(Attribute::StrictFP)) {
+      F->addFnAttr(Attribute::StrictFP);
+    }
+  }
+
+  void setConstrainedFPCallAttr(CallInst *I) {
+    if (!I->hasFnAttr(Attribute::StrictFP))
+      I->addAttribute(AttributeList::FunctionIndex, Attribute::StrictFP);
+    setConstrainedFPFunctionAttr();
+  }
+
   //===--------------------------------------------------------------------===//
   // RAII helpers.
   //===--------------------------------------------------------------------===//
@@ -1479,6 +1494,8 @@
 
     CallInst *C = CreateIntrinsic(ID, {L->getType()},
                                   {L, R, RoundingV, ExceptV}, nullptr, Name);
+    setConstrainedFPCallAttr(C);
+
     return cast<CallInst>(setFPAttrs(C, FPMathTag, UseFMF));
   }
 
@@ -2083,6 +2100,8 @@
                           Name);
       break;
     }
+    setConstrainedFPCallAttr(C);
+
     if (isa<FPMathOperator>(C))
       C = cast<CallInst>(setFPAttrs(C, FPMathTag, UseFMF));
     return C;
@@ -2239,6 +2258,8 @@
                        ArrayRef<Value *> Args = None, const Twine &Name = "",
                        MDNode *FPMathTag = nullptr) {
     CallInst *CI = CallInst::Create(FTy, Callee, Args, DefaultOperandBundles);
+    if (IsFPConstrained)
+      setConstrainedFPCallAttr(CI);
     if (isa<FPMathOperator>(CI))
       CI = cast<CallInst>(setFPAttrs(CI, FPMathTag, FMF));
     return Insert(CI, Name);
@@ -2248,6 +2269,8 @@
                        ArrayRef<OperandBundleDef> OpBundles,
                        const Twine &Name = "", MDNode *FPMathTag = nullptr) {
     CallInst *CI = CallInst::Create(FTy, Callee, Args, OpBundles);
+    if (IsFPConstrained)
+      setConstrainedFPCallAttr(CI);
     if (isa<FPMathOperator>(CI))
       CI = cast<CallInst>(setFPAttrs(CI, FPMathTag, FMF));
     return Insert(CI, Name);


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