[llvm] r230241 - Prevent hoisting fmul from THEN/ELSE to IF if there is fmsub/fmadd opportunity.
Chad Rosier
mcrosier at codeaurora.org
Mon Feb 23 11:15:17 PST 2015
Author: mcrosier
Date: Mon Feb 23 13:15:16 2015
New Revision: 230241
URL: http://llvm.org/viewvc/llvm-project?rev=230241&view=rev
Log:
Prevent hoisting fmul from THEN/ELSE to IF if there is fmsub/fmadd opportunity.
This patch adds the isProfitableToHoist API. For AArch64, we want to prevent a
fmul from being hoisted in cases where it is more profitable to form a
fmsub/fmadd.
Phabricator Review: http://reviews.llvm.org/D7299
Patch by Lawrence Hu <lawrence at codeaurora.org>
Added:
llvm/trunk/test/Transforms/SimplifyCFG/AArch64/
llvm/trunk/test/Transforms/SimplifyCFG/AArch64/lit.local.cfg
llvm/trunk/test/Transforms/SimplifyCFG/AArch64/prefer-fma.ll
Modified:
llvm/trunk/include/llvm/Analysis/TargetTransformInfo.h
llvm/trunk/include/llvm/Analysis/TargetTransformInfoImpl.h
llvm/trunk/include/llvm/CodeGen/BasicTTIImpl.h
llvm/trunk/include/llvm/Target/TargetLowering.h
llvm/trunk/lib/Analysis/TargetTransformInfo.cpp
llvm/trunk/lib/Target/AArch64/AArch64ISelLowering.cpp
llvm/trunk/lib/Target/AArch64/AArch64ISelLowering.h
llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp
Modified: llvm/trunk/include/llvm/Analysis/TargetTransformInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/TargetTransformInfo.h?rev=230241&r1=230240&r2=230241&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Analysis/TargetTransformInfo.h (original)
+++ llvm/trunk/include/llvm/Analysis/TargetTransformInfo.h Mon Feb 23 13:15:16 2015
@@ -313,6 +313,10 @@ public:
/// by referencing its sub-register AX.
bool isTruncateFree(Type *Ty1, Type *Ty2) const;
+ /// \brief Return true if it is profitable to hoist instruction in the
+ /// then/else to before if.
+ bool isProfitableToHoist(Instruction *I) const;
+
/// \brief Return true if this type is legal.
bool isTypeLegal(Type *Ty) const;
@@ -521,6 +525,7 @@ public:
int64_t BaseOffset, bool HasBaseReg,
int64_t Scale) = 0;
virtual bool isTruncateFree(Type *Ty1, Type *Ty2) = 0;
+ virtual bool isProfitableToHoist(Instruction *I) = 0;
virtual bool isTypeLegal(Type *Ty) = 0;
virtual unsigned getJumpBufAlignment() = 0;
virtual unsigned getJumpBufSize() = 0;
@@ -633,6 +638,9 @@ public:
bool isTruncateFree(Type *Ty1, Type *Ty2) override {
return Impl.isTruncateFree(Ty1, Ty2);
}
+ bool isProfitableToHoist(Instruction *I) override {
+ return Impl.isProfitableToHoist(I);
+ }
bool isTypeLegal(Type *Ty) override { return Impl.isTypeLegal(Ty); }
unsigned getJumpBufAlignment() override { return Impl.getJumpBufAlignment(); }
unsigned getJumpBufSize() override { return Impl.getJumpBufSize(); }
Modified: llvm/trunk/include/llvm/Analysis/TargetTransformInfoImpl.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/TargetTransformInfoImpl.h?rev=230241&r1=230240&r2=230241&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Analysis/TargetTransformInfoImpl.h (original)
+++ llvm/trunk/include/llvm/Analysis/TargetTransformInfoImpl.h Mon Feb 23 13:15:16 2015
@@ -225,6 +225,8 @@ public:
bool isTruncateFree(Type *Ty1, Type *Ty2) { return false; }
+ bool isProfitableToHoist(Instruction *I) { return true; }
+
bool isTypeLegal(Type *Ty) { return false; }
unsigned getJumpBufAlignment() { return 0; }
Modified: llvm/trunk/include/llvm/CodeGen/BasicTTIImpl.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/BasicTTIImpl.h?rev=230241&r1=230240&r2=230241&view=diff
==============================================================================
--- llvm/trunk/include/llvm/CodeGen/BasicTTIImpl.h (original)
+++ llvm/trunk/include/llvm/CodeGen/BasicTTIImpl.h Mon Feb 23 13:15:16 2015
@@ -145,6 +145,10 @@ public:
return getTLI()->isTruncateFree(Ty1, Ty2);
}
+ bool isProfitableToHoist(Instruction *I) {
+ return getTLI()->isProfitableToHoist(I);
+ }
+
bool isTypeLegal(Type *Ty) {
EVT VT = getTLI()->getValueType(Ty);
return getTLI()->isTypeLegal(VT);
Modified: llvm/trunk/include/llvm/Target/TargetLowering.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Target/TargetLowering.h?rev=230241&r1=230240&r2=230241&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Target/TargetLowering.h (original)
+++ llvm/trunk/include/llvm/Target/TargetLowering.h Mon Feb 23 13:15:16 2015
@@ -1456,6 +1456,8 @@ public:
return false;
}
+ virtual bool isProfitableToHoist(Instruction *I) const { return true; }
+
/// Return true if any actual instruction that defines a value of type Ty1
/// implicitly zero-extends the value to Ty2 in the result register.
///
Modified: llvm/trunk/lib/Analysis/TargetTransformInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/TargetTransformInfo.cpp?rev=230241&r1=230240&r2=230241&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/TargetTransformInfo.cpp (original)
+++ llvm/trunk/lib/Analysis/TargetTransformInfo.cpp Mon Feb 23 13:15:16 2015
@@ -123,6 +123,10 @@ bool TargetTransformInfo::isTruncateFree
return TTIImpl->isTruncateFree(Ty1, Ty2);
}
+bool TargetTransformInfo::isProfitableToHoist(Instruction *I) const {
+ return TTIImpl->isProfitableToHoist(I);
+}
+
bool TargetTransformInfo::isTypeLegal(Type *Ty) const {
return TTIImpl->isTypeLegal(Ty);
}
Modified: llvm/trunk/lib/Target/AArch64/AArch64ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/AArch64/AArch64ISelLowering.cpp?rev=230241&r1=230240&r2=230241&view=diff
==============================================================================
--- llvm/trunk/lib/Target/AArch64/AArch64ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/AArch64/AArch64ISelLowering.cpp Mon Feb 23 13:15:16 2015
@@ -6533,6 +6533,34 @@ bool AArch64TargetLowering::isTruncateFr
return NumBits1 > NumBits2;
}
+/// Check if it is profitable to hoist instruction in then/else to if.
+/// Not profitable if I and it's user can form a FMA instruction
+/// because we prefer FMSUB/FMADD.
+bool AArch64TargetLowering::isProfitableToHoist(Instruction *I) const {
+ if (I->getOpcode() != Instruction::FMul)
+ return true;
+
+ if (I->getNumUses() != 1)
+ return true;
+
+ Instruction *User = I->user_back();
+
+ if (User &&
+ !(User->getOpcode() == Instruction::FSub ||
+ User->getOpcode() == Instruction::FAdd))
+ return true;
+
+ const TargetOptions &Options = getTargetMachine().Options;
+ EVT VT = getValueType(User->getOperand(0)->getType());
+
+ if (isFMAFasterThanFMulAndFAdd(VT) &&
+ isOperationLegalOrCustom(ISD::FMA, VT) &&
+ (Options.AllowFPOpFusion == FPOpFusion::Fast || Options.UnsafeFPMath))
+ return false;
+
+ return true;
+}
+
// All 32-bit GPR operations implicitly zero the high-half of the corresponding
// 64-bit GPR.
bool AArch64TargetLowering::isZExtFree(Type *Ty1, Type *Ty2) const {
Modified: llvm/trunk/lib/Target/AArch64/AArch64ISelLowering.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/AArch64/AArch64ISelLowering.h?rev=230241&r1=230240&r2=230241&view=diff
==============================================================================
--- llvm/trunk/lib/Target/AArch64/AArch64ISelLowering.h (original)
+++ llvm/trunk/lib/Target/AArch64/AArch64ISelLowering.h Mon Feb 23 13:15:16 2015
@@ -18,6 +18,7 @@
#include "llvm/CodeGen/CallingConvLower.h"
#include "llvm/CodeGen/SelectionDAG.h"
#include "llvm/IR/CallingConv.h"
+#include "llvm/IR/Instruction.h"
#include "llvm/Target/TargetLowering.h"
namespace llvm {
@@ -286,6 +287,8 @@ public:
bool isTruncateFree(Type *Ty1, Type *Ty2) const override;
bool isTruncateFree(EVT VT1, EVT VT2) const override;
+ bool isProfitableToHoist(Instruction *I) const override;
+
bool isZExtFree(Type *Ty1, Type *Ty2) const override;
bool isZExtFree(EVT VT1, EVT VT2) const override;
bool isZExtFree(SDValue Val, EVT VT2) const override;
Modified: llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp?rev=230241&r1=230240&r2=230241&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp Mon Feb 23 13:15:16 2015
@@ -1053,7 +1053,8 @@ static bool passingValueIsAlwaysUndefine
/// HoistThenElseCodeToIf - Given a conditional branch that goes to BB1 and
/// BB2, hoist any common code in the two blocks up into the branch block. The
/// caller of this function guarantees that BI's block dominates BB1 and BB2.
-static bool HoistThenElseCodeToIf(BranchInst *BI, const DataLayout *DL) {
+static bool HoistThenElseCodeToIf(BranchInst *BI, const DataLayout *DL,
+ const TargetTransformInfo &TTI) {
// This does very trivial matching, with limited scanning, to find identical
// instructions in the two blocks. In particular, we don't want to get into
// O(M*N) situations here where M and N are the sizes of BB1 and BB2. As
@@ -1088,6 +1089,9 @@ static bool HoistThenElseCodeToIf(Branch
if (isa<TerminatorInst>(I1))
goto HoistTerminator;
+ if (!TTI.isProfitableToHoist(I1) || !TTI.isProfitableToHoist(I2))
+ return Changed;
+
// For a normal instruction, we just move one to right before the branch,
// then replace all uses of the other with the first. Finally, we remove
// the now redundant second instruction.
@@ -4442,7 +4446,7 @@ bool SimplifyCFGOpt::SimplifyCondBranch(
// can hoist it up to the branching block.
if (BI->getSuccessor(0)->getSinglePredecessor()) {
if (BI->getSuccessor(1)->getSinglePredecessor()) {
- if (HoistThenElseCodeToIf(BI, DL))
+ if (HoistThenElseCodeToIf(BI, DL, TTI))
return SimplifyCFG(BB, TTI, BonusInstThreshold, DL, AC) | true;
} else {
// If Successor #1 has multiple preds, we may be able to conditionally
Added: llvm/trunk/test/Transforms/SimplifyCFG/AArch64/lit.local.cfg
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SimplifyCFG/AArch64/lit.local.cfg?rev=230241&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/SimplifyCFG/AArch64/lit.local.cfg (added)
+++ llvm/trunk/test/Transforms/SimplifyCFG/AArch64/lit.local.cfg Mon Feb 23 13:15:16 2015
@@ -0,0 +1,5 @@
+config.suffixes = ['.ll']
+
+targets = set(config.root.targets_to_build.split())
+if not 'AArch64' in targets:
+ config.unsupported = True
Added: llvm/trunk/test/Transforms/SimplifyCFG/AArch64/prefer-fma.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SimplifyCFG/AArch64/prefer-fma.ll?rev=230241&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/SimplifyCFG/AArch64/prefer-fma.ll (added)
+++ llvm/trunk/test/Transforms/SimplifyCFG/AArch64/prefer-fma.ll Mon Feb 23 13:15:16 2015
@@ -0,0 +1,72 @@
+; RUN: opt < %s -mtriple=aarch64-linux-gnu -simplifycfg -enable-unsafe-fp-math -S >%t
+; RUN: FileCheck %s < %t
+; ModuleID = 't.cc'
+
+; Function Attrs: nounwind
+define double @_Z3fooRdS_S_S_(double* dereferenceable(8) %x, double* dereferenceable(8) %y, double* dereferenceable(8) %a) #0 {
+entry:
+ %0 = load double* %y, align 8
+ %cmp = fcmp oeq double %0, 0.000000e+00
+ %1 = load double* %x, align 8
+ br i1 %cmp, label %if.then, label %if.else
+
+; fadd (const, (fmul x, y))
+if.then: ; preds = %entry
+; CHECK-LABEL: if.then:
+; CHECK: %3 = fmul fast double %1, %2
+; CHECK-NEXT: %mul = fadd fast double 1.000000e+00, %3
+ %2 = load double* %a, align 8
+ %3 = fmul fast double %1, %2
+ %mul = fadd fast double 1.000000e+00, %3
+ store double %mul, double* %y, align 8
+ br label %if.end
+
+; fsub ((fmul x, y), z)
+if.else: ; preds = %entry
+; CHECK-LABEL: if.else:
+; CHECK: %mul1 = fmul fast double %1, %2
+; CHECK-NEXT: %sub1 = fsub fast double %mul1, %0
+ %4 = load double* %a, align 8
+ %mul1 = fmul fast double %1, %4
+ %sub1 = fsub fast double %mul1, %0
+ store double %sub1, double* %y, align 8
+ br label %if.end
+
+if.end: ; preds = %if.else, %if.then
+ %5 = load double* %y, align 8
+ %cmp2 = fcmp oeq double %5, 2.000000e+00
+ %6 = load double* %x, align 8
+ br i1 %cmp2, label %if.then2, label %if.else2
+
+; fsub (x, (fmul y, z))
+if.then2: ; preds = %entry
+; CHECK-LABEL: if.then2:
+; CHECK: %7 = fmul fast double %5, 3.000000e+00
+; CHECK-NEXT: %mul2 = fsub fast double %6, %7
+ %7 = load double* %a, align 8
+ %8 = fmul fast double %6, 3.0000000e+00
+ %mul2 = fsub fast double %7, %8
+ store double %mul2, double* %y, align 8
+ br label %if.end2
+
+; fsub (fneg((fmul x, y)), const)
+if.else2: ; preds = %entry
+; CHECK-LABEL: if.else2:
+; CHECK: %mul3 = fmul fast double %5, 3.000000e+00
+; CHECK-NEXT: %neg = fsub fast double 0.000000e+00, %mul3
+; CHECK-NEXT: %sub2 = fsub fast double %neg, 3.000000e+00
+ %mul3 = fmul fast double %6, 3.0000000e+00
+ %neg = fsub fast double 0.0000000e+00, %mul3
+ %sub2 = fsub fast double %neg, 3.0000000e+00
+ store double %sub2, double* %y, align 8
+ br label %if.end2
+
+if.end2: ; preds = %if.else, %if.then
+ %9 = load double* %x, align 8
+ %10 = load double* %y, align 8
+ %add = fadd fast double %9, %10
+ %11 = load double* %a, align 8
+ %add2 = fadd fast double %add, %11
+ ret double %add2
+}
+
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