From 17aa156fe7c01b447d3222c0bf330f6510a0d524 Mon Sep 17 00:00:00 2001
From: "Kevin P. Neal" <kevin.neal@sas.com>
Date: Thu, 18 Jul 2019 18:01:57 +0000
Subject: [PATCH] [FPEnv] Teach the IRBuilder about constrained FPTrunc and
 FPExt

The IRBuilder doesn't know that FPTrunc and FPExt have constrained
equivalents. Add the support by building on the strict FP mode now
present in the IRBuilder.

Reviewed by:	John McCall
Approved by:	John McCall
Differential Revision:	https://reviews.llvm.org/D64934

llvm-svn: 366477
---
 include/llvm/IR/IRBuilder.h    | 30 ++++++++++++++++++++++++++++++
 unittests/IR/IRBuilderTest.cpp | 14 ++++++++++++++
 2 files changed, 44 insertions(+)

diff --git a/include/llvm/IR/IRBuilder.h b/include/llvm/IR/IRBuilder.h
index a74364dffb2..88630f56038 100644
--- a/include/llvm/IR/IRBuilder.h
+++ b/include/llvm/IR/IRBuilder.h
@@ -1931,10 +1931,17 @@ public:
 
   Value *CreateFPTrunc(Value *V, Type *DestTy,
                        const Twine &Name = "") {
+    if (IsFPConstrained)
+      return CreateConstrainedFPCast(
+          Intrinsic::experimental_constrained_fptrunc, V, DestTy, nullptr,
+          Name);
     return CreateCast(Instruction::FPTrunc, V, DestTy, Name);
   }
 
   Value *CreateFPExt(Value *V, Type *DestTy, const Twine &Name = "") {
+    if (IsFPConstrained)
+      return CreateConstrainedFPCast(Intrinsic::experimental_constrained_fpext,
+                                     V, DestTy, nullptr, Name);
     return CreateCast(Instruction::FPExt, V, DestTy, Name);
   }
 
@@ -2046,6 +2053,29 @@ public:
     return Insert(CastInst::CreateFPCast(V, DestTy), Name);
   }
 
+  CallInst *CreateConstrainedFPCast(
+      Intrinsic::ID ID, Value *V, Type *DestTy,
+      Instruction *FMFSource = nullptr, const Twine &Name = "",
+      MDNode *FPMathTag = nullptr,
+      Optional<ConstrainedFPIntrinsic::RoundingMode> Rounding = None,
+      Optional<ConstrainedFPIntrinsic::ExceptionBehavior> Except = None) {
+    Value *RoundingV = getConstrainedFPRounding(Rounding);
+    Value *ExceptV = getConstrainedFPExcept(Except);
+
+    FastMathFlags UseFMF = FMF;
+    if (FMFSource)
+      UseFMF = FMFSource->getFastMathFlags();
+
+    CallInst *C;
+    if (ID == Intrinsic::experimental_constrained_fpext)
+      C = CreateIntrinsic(ID, {DestTy, V->getType()}, {V, ExceptV}, nullptr,
+                          Name);
+    else
+      C = CreateIntrinsic(ID, {DestTy, V->getType()}, {V, RoundingV, ExceptV},
+                          nullptr, Name);
+    return cast<CallInst>(setFPAttrs(C, FPMathTag, UseFMF));
+  }
+
   // Provided to resolve 'CreateIntCast(Ptr, Ptr, "...")', giving a
   // compile time error, instead of converting the string to bool for the
   // isSigned parameter.
diff --git a/unittests/IR/IRBuilderTest.cpp b/unittests/IR/IRBuilderTest.cpp
index 667b9ef0319..f73cf140e19 100644
--- a/unittests/IR/IRBuilderTest.cpp
+++ b/unittests/IR/IRBuilderTest.cpp
@@ -125,10 +125,14 @@ TEST_F(IRBuilderTest, Intrinsics) {
 TEST_F(IRBuilderTest, ConstrainedFP) {
   IRBuilder<> Builder(BB);
   Value *V;
+  Value *VDouble;
   CallInst *Call;
   IntrinsicInst *II;
+  GlobalVariable *GVDouble = new GlobalVariable(*M, Type::getDoubleTy(Ctx),
+                            true, GlobalValue::ExternalLinkage, nullptr);
 
   V = Builder.CreateLoad(GV->getValueType(), GV);
+  VDouble = Builder.CreateLoad(GVDouble->getValueType(), GVDouble);
 
   // See if we get constrained intrinsics instead of non-constrained
   // instructions.
@@ -159,6 +163,16 @@ TEST_F(IRBuilderTest, ConstrainedFP) {
   II = cast<IntrinsicInst>(V);
   EXPECT_EQ(II->getIntrinsicID(), Intrinsic::experimental_constrained_frem);
 
+  V = Builder.CreateFPTrunc(VDouble, Type::getFloatTy(Ctx));
+  ASSERT_TRUE(isa<IntrinsicInst>(V));
+  II = cast<IntrinsicInst>(V);
+  EXPECT_EQ(II->getIntrinsicID(), Intrinsic::experimental_constrained_fptrunc);
+
+  VDouble = Builder.CreateFPExt(V, Type::getDoubleTy(Ctx));
+  ASSERT_TRUE(isa<IntrinsicInst>(VDouble));
+  II = cast<IntrinsicInst>(VDouble);
+  EXPECT_EQ(II->getIntrinsicID(), Intrinsic::experimental_constrained_fpext);
+
   // Verify the codepaths for setting and overriding the default metadata.
   V = Builder.CreateFAdd(V, V);
   ASSERT_TRUE(isa<ConstrainedFPIntrinsic>(V));