From 4e8598eee3575db313966f24ffb116e06d38ea9c Mon Sep 17 00:00:00 2001
From: Michael Zolotukhin <mzolotukhin@apple.com>
Date: Fri, 6 Feb 2015 20:02:51 +0000
Subject: [InstSimplify] Add SimplifyFPBinOp function.

It is a variation of SimplifyBinOp, but it takes into account
FastMathFlags.

It is needed in inliner and loop-unroller to accurately predict the
transformation's outcome (previously we dropped the flags and were too
conservative in some cases).

Example:
float foo(float *a, float b) {
 float r;
 if (a[1] * b)
   r = /* a lot of expensive computations */;
 else
   r = 1;
 return r;
}
float boo(float *a) {
 return foo(a, 0.0);
}

Without this patch, we don't inline 'foo' into 'boo'.

llvm-svn: 228432
---
 llvm/lib/Analysis/InstructionSimplify.cpp | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

(limited to 'llvm/lib/Analysis/InstructionSimplify.cpp')

diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index 588d625910f..d02bb2b8f52 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -61,6 +61,8 @@ struct Query {
 static Value *SimplifyAndInst(Value *, Value *, const Query &, unsigned);
 static Value *SimplifyBinOp(unsigned, Value *, Value *, const Query &,
                             unsigned);
+static Value *SimplifyFPBinOp(unsigned, Value *, Value *, const FastMathFlags &,
+                              const Query &, unsigned);
 static Value *SimplifyCmpInst(unsigned, Value *, Value *, const Query &,
                               unsigned);
 static Value *SimplifyOrInst(Value *, Value *, const Query &, unsigned);
@@ -3465,6 +3467,25 @@ static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
   }
 }
 
+/// SimplifyFPBinOp - Given operands for a BinaryOperator, see if we can
+/// fold the result.  If not, this returns null.
+/// In contrast to SimplifyBinOp, try to use FastMathFlag when folding the
+/// result. In case we don't need FastMathFlags, simply fall to SimplifyBinOp.
+static Value *SimplifyFPBinOp(unsigned Opcode, Value *LHS, Value *RHS,
+                              const FastMathFlags &FMF, const Query &Q,
+                              unsigned MaxRecurse) {
+  switch (Opcode) {
+  case Instruction::FAdd:
+    return SimplifyFAddInst(LHS, RHS, FMF, Q, MaxRecurse);
+  case Instruction::FSub:
+    return SimplifyFSubInst(LHS, RHS, FMF, Q, MaxRecurse);
+  case Instruction::FMul:
+    return SimplifyFMulInst(LHS, RHS, FMF, Q, MaxRecurse);
+  default:
+    return SimplifyBinOp(Opcode, LHS, RHS, Q, MaxRecurse);
+  }
+}
+
 Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
                            const DataLayout *DL, const TargetLibraryInfo *TLI,
                            const DominatorTree *DT, AssumptionCache *AC,
@@ -3473,6 +3494,15 @@ Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
                          RecursionLimit);
 }
 
+Value *llvm::SimplifyFPBinOp(unsigned Opcode, Value *LHS, Value *RHS,
+                             const FastMathFlags &FMF, const DataLayout *DL,
+                             const TargetLibraryInfo *TLI,
+                             const DominatorTree *DT, AssumptionCache *AC,
+                             const Instruction *CxtI) {
+  return ::SimplifyFPBinOp(Opcode, LHS, RHS, FMF, Query(DL, TLI, DT, AC, CxtI),
+                           RecursionLimit);
+}
+
 /// SimplifyCmpInst - Given operands for a CmpInst, see if we can
 /// fold the result.
 static Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
-- 
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