[llvm] r245921 - Pass function attributes instead of boolean in isIntDivCheap().
Mehdi Amini via llvm-commits
llvm-commits at lists.llvm.org
Mon Aug 24 22:37:58 PDT 2015
That was his original idea, but I suggested to pass the attribute if it is what you’re interested it. I tend to prefer being more specific when we can.
What makes you feel we would better pass the function in this case?
—
Mehdi
> On Aug 24, 2015, at 7:53 PM, Eric Christopher via llvm-commits <llvm-commits at lists.llvm.org> wrote:
>
> Bike shed: how about pass the function around instead.
>
>
> On Mon, Aug 24, 2015, 7:32 PM Steve King via llvm-commits <llvm-commits at lists.llvm.org <mailto:llvm-commits at lists.llvm.org>> wrote:
> Author: srking
> Date: Mon Aug 24 21:31:21 2015
> New Revision: 245921
>
> URL: http://llvm.org/viewvc/llvm-project?rev=245921&view=rev <https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_viewvc_llvm-2Dproject-3Frev-3D245921-26view-3Drev&d=BQMFaQ&c=eEvniauFctOgLOKGJOplqw&r=v-ruWq0KCv2O3thJZiK6naxuXK8mQHZUmGq5FBtAmZ4&m=qk06_-wcwq7eqO7LUFPzl1Aq74j2Wtt1OYSdzi_XD6w&s=MK1uk2OxcL4E_0oeST7aCNaBTxU_YUYiHWCDi5wZH8k&e=>
> Log:
> Pass function attributes instead of boolean in isIntDivCheap().
>
> Added:
> llvm/trunk/test/CodeGen/X86/sdiv-pow2.ll
> Modified:
> llvm/trunk/include/llvm/Target/TargetLowering.h
> llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
> llvm/trunk/lib/CodeGen/SelectionDAG/TargetLowering.cpp
> llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
> llvm/trunk/lib/Target/X86/X86ISelLowering.h
>
> Modified: llvm/trunk/include/llvm/Target/TargetLowering.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Target/TargetLowering.h?rev=245921&r1=245920&r2=245921&view=diff <https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_viewvc_llvm-2Dproject_llvm_trunk_include_llvm_Target_TargetLowering.h-3Frev-3D245921-26r1-3D245920-26r2-3D245921-26view-3Ddiff&d=BQMFaQ&c=eEvniauFctOgLOKGJOplqw&r=v-ruWq0KCv2O3thJZiK6naxuXK8mQHZUmGq5FBtAmZ4&m=qk06_-wcwq7eqO7LUFPzl1Aq74j2Wtt1OYSdzi_XD6w&s=qWvlrkYX2cLwOMB7E9EjhDVi58YD9OSONOmy7M88428&e=>
> ==============================================================================
> --- llvm/trunk/include/llvm/Target/TargetLowering.h (original)
> +++ llvm/trunk/include/llvm/Target/TargetLowering.h Mon Aug 24 21:31:21 2015
> @@ -228,7 +228,7 @@ public:
> /// several shifts, adds, and multiplies for this target.
> /// The definition of "cheaper" may depend on whether we're optimizing
> /// for speed or for size.
> - virtual bool isIntDivCheap(EVT VT, bool OptSize) const {
> + virtual bool isIntDivCheap(EVT VT, AttributeSet Attr) const {
> return false;
> }
>
> @@ -2719,11 +2719,14 @@ public:
> SDValue BuildUDIV(SDNode *N, const APInt &Divisor, SelectionDAG &DAG,
> bool IsAfterLegalization,
> std::vector<SDNode *> *Created) const;
> +
> + /// Targets may override this function to provide custom SDIV lowering for
> + /// power-of-2 denominators. If the target returns an empty SDValue, LLVM
> + /// assumes SDIV is expensive and replaces it with a series of other integer
> + /// operations.
> virtual SDValue BuildSDIVPow2(SDNode *N, const APInt &Divisor,
> SelectionDAG &DAG,
> - std::vector<SDNode *> *Created) const {
> - return SDValue();
> - }
> + std::vector<SDNode *> *Created) const;
>
> /// Indicate whether this target prefers to combine FDIVs with the same
> /// divisor. If the transform should never be done, return zero. If the
>
> Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=245921&r1=245920&r2=245921&view=diff <https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_viewvc_llvm-2Dproject_llvm_trunk_lib_CodeGen_SelectionDAG_DAGCombiner.cpp-3Frev-3D245921-26r1-3D245920-26r2-3D245921-26view-3Ddiff&d=BQMFaQ&c=eEvniauFctOgLOKGJOplqw&r=v-ruWq0KCv2O3thJZiK6naxuXK8mQHZUmGq5FBtAmZ4&m=qk06_-wcwq7eqO7LUFPzl1Aq74j2Wtt1OYSdzi_XD6w&s=IWTRWAXNbgIwcgdUr8HMgcXpQnsbGZ9LVqQZmNQrrf4&e=>
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
> +++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Mon Aug 24 21:31:21 2015
> @@ -2183,7 +2183,6 @@ SDValue DAGCombiner::visitSDIV(SDNode *N
> N0, N1);
> }
>
> - bool MinSize = DAG.getMachineFunction().getFunction()->optForMinSize();
> // fold (sdiv X, pow2) -> simple ops after legalize
> // FIXME: We check for the exact bit here because the generic lowering gives
> // better results in that case. The target-specific lowering should learn how
> @@ -2192,10 +2191,6 @@ SDValue DAGCombiner::visitSDIV(SDNode *N
> !cast<BinaryWithFlagsSDNode>(N)->Flags.hasExact() &&
> (N1C->getAPIntValue().isPowerOf2() ||
> (-N1C->getAPIntValue()).isPowerOf2())) {
> - // If integer division is cheap, then don't perform the following fold.
> - if (TLI.isIntDivCheap(N->getValueType(0), MinSize))
> - return SDValue();
> -
> // Target-specific implementation of sdiv x, pow2.
> if (SDValue Res = BuildSDIVPow2(N))
> return Res;
> @@ -2232,8 +2227,10 @@ SDValue DAGCombiner::visitSDIV(SDNode *N
> }
>
> // If integer divide is expensive and we satisfy the requirements, emit an
> - // alternate sequence.
> - if (N1C && !TLI.isIntDivCheap(N->getValueType(0), MinSize))
> + // alternate sequence. Targets may check function attributes for size/speed
> + // trade-offs.
> + AttributeSet Attr = DAG.getMachineFunction().getFunction()->getAttributes();
> + if (N1C && !TLI.isIntDivCheap(N->getValueType(0), Attr))
> if (SDValue Op = BuildSDIV(N))
> return Op;
>
> @@ -2289,8 +2286,8 @@ SDValue DAGCombiner::visitUDIV(SDNode *N
> }
>
> // fold (udiv x, c) -> alternate
> - bool MinSize = DAG.getMachineFunction().getFunction()->optForMinSize();
> - if (N1C && !TLI.isIntDivCheap(N->getValueType(0), MinSize))
> + AttributeSet Attr = DAG.getMachineFunction().getFunction()->getAttributes();
> + if (N1C && !TLI.isIntDivCheap(N->getValueType(0), Attr))
> if (SDValue Op = BuildUDIV(N))
> return Op;
>
>
> Modified: llvm/trunk/lib/CodeGen/SelectionDAG/TargetLowering.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/TargetLowering.cpp?rev=245921&r1=245920&r2=245921&view=diff <https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_viewvc_llvm-2Dproject_llvm_trunk_lib_CodeGen_SelectionDAG_TargetLowering.cpp-3Frev-3D245921-26r1-3D245920-26r2-3D245921-26view-3Ddiff&d=BQMFaQ&c=eEvniauFctOgLOKGJOplqw&r=v-ruWq0KCv2O3thJZiK6naxuXK8mQHZUmGq5FBtAmZ4&m=qk06_-wcwq7eqO7LUFPzl1Aq74j2Wtt1OYSdzi_XD6w&s=nnvowLjLP805dYgRM9eY_Ha5WDaQOsYfaPl-vXdHl1I&e=>
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/SelectionDAG/TargetLowering.cpp (original)
> +++ llvm/trunk/lib/CodeGen/SelectionDAG/TargetLowering.cpp Mon Aug 24 21:31:21 2015
> @@ -2725,6 +2725,16 @@ static SDValue BuildExactSDIV(const Targ
> return Mul;
> }
>
> +SDValue TargetLowering::BuildSDIVPow2(SDNode *N, const APInt &Divisor,
> + SelectionDAG &DAG,
> + std::vector<SDNode *> *Created) const {
> + AttributeSet Attr = DAG.getMachineFunction().getFunction()->getAttributes();
> + const TargetLowering &TLI = DAG.getTargetLoweringInfo();
> + if (TLI.isIntDivCheap(N->getValueType(0), Attr))
> + return SDValue(N,0); // Lower SDIV as SDIV
> + return SDValue();
> +}
> +
> /// \brief Given an ISD::SDIV node expressing a divide by constant,
> /// return a DAG expression to select that will generate the same value by
> /// multiplying by a magic number.
>
> Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=245921&r1=245920&r2=245921&view=diff <https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_viewvc_llvm-2Dproject_llvm_trunk_lib_Target_X86_X86ISelLowering.cpp-3Frev-3D245921-26r1-3D245920-26r2-3D245921-26view-3Ddiff&d=BQMFaQ&c=eEvniauFctOgLOKGJOplqw&r=v-ruWq0KCv2O3thJZiK6naxuXK8mQHZUmGq5FBtAmZ4&m=qk06_-wcwq7eqO7LUFPzl1Aq74j2Wtt1OYSdzi_XD6w&s=nrhR14-a-Lm9_bQ4zUK34m2l73TImMiFsDD75mbyybM&e=>
> ==============================================================================
> --- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
> +++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Mon Aug 24 21:31:21 2015
> @@ -26511,7 +26511,7 @@ bool X86TargetLowering::isTargetFTOL() c
> return Subtarget->isTargetKnownWindowsMSVC() && !Subtarget->is64Bit();
> }
>
> -bool X86TargetLowering::isIntDivCheap(EVT VT, bool OptSize) const {
> +bool X86TargetLowering::isIntDivCheap(EVT VT, AttributeSet Attr) const {
> // Integer division on x86 is expensive. However, when aggressively optimizing
> // for code size, we prefer to use a div instruction, as it is usually smaller
> // than the alternative sequence.
> @@ -26519,5 +26519,7 @@ bool X86TargetLowering::isIntDivCheap(EV
> // integer division, leaving the division as-is is a loss even in terms of
> // size, because it will have to be scalarized, while the alternative code
> // sequence can be performed in vector form.
> + bool OptSize = Attr.hasAttribute(AttributeSet::FunctionIndex,
> + Attribute::MinSize);
> return OptSize && !VT.isVector();
> }
>
> Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.h?rev=245921&r1=245920&r2=245921&view=diff <https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_viewvc_llvm-2Dproject_llvm_trunk_lib_Target_X86_X86ISelLowering.h-3Frev-3D245921-26r1-3D245920-26r2-3D245921-26view-3Ddiff&d=BQMFaQ&c=eEvniauFctOgLOKGJOplqw&r=v-ruWq0KCv2O3thJZiK6naxuXK8mQHZUmGq5FBtAmZ4&m=qk06_-wcwq7eqO7LUFPzl1Aq74j2Wtt1OYSdzi_XD6w&s=ifspFjmLjzkRdQA76sIYpkMhi9bvAOXSfiPwZSBOd6M&e=>
> ==============================================================================
> --- llvm/trunk/lib/Target/X86/X86ISelLowering.h (original)
> +++ llvm/trunk/lib/Target/X86/X86ISelLowering.h Mon Aug 24 21:31:21 2015
> @@ -902,7 +902,7 @@ namespace llvm {
> /// \brief Customize the preferred legalization strategy for certain types.
> LegalizeTypeAction getPreferredVectorAction(EVT VT) const override;
>
> - bool isIntDivCheap(EVT VT, bool OptSize) const override;
> + bool isIntDivCheap(EVT VT, AttributeSet Attr) const override;
>
> protected:
> std::pair<const TargetRegisterClass *, uint8_t>
>
> Added: llvm/trunk/test/CodeGen/X86/sdiv-pow2.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/sdiv-pow2.ll?rev=245921&view=auto <https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.org_viewvc_llvm-2Dproject_llvm_trunk_test_CodeGen_X86_sdiv-2Dpow2.ll-3Frev-3D245921-26view-3Dauto&d=BQMFaQ&c=eEvniauFctOgLOKGJOplqw&r=v-ruWq0KCv2O3thJZiK6naxuXK8mQHZUmGq5FBtAmZ4&m=qk06_-wcwq7eqO7LUFPzl1Aq74j2Wtt1OYSdzi_XD6w&s=ZLxX-rykG7N8rahm-kJAjuq0aBYsrlkuU0LsAHmBHy8&e=>
> ==============================================================================
> --- llvm/trunk/test/CodeGen/X86/sdiv-pow2.ll (added)
> +++ llvm/trunk/test/CodeGen/X86/sdiv-pow2.ll Mon Aug 24 21:31:21 2015
> @@ -0,0 +1,33 @@
> +; RUN: llc -march=x86 < %s | FileCheck %s
> +
> +; No attributes, should not use idiv
> +define i32 @test1(i32 inreg %x) {
> +entry:
> + %div = sdiv i32 %x, 16
> + ret i32 %div
> +; CHECK-LABEL: test1:
> +; CHECK-NOT: idivl
> +; CHECK: ret
> +}
> +
> +; Has minsize (-Oz) attribute, should generate idiv
> +define i32 @test2(i32 inreg %x) minsize {
> +entry:
> + %div = sdiv i32 %x, 16
> + ret i32 %div
> +; CHECK-LABEL: test2:
> +; CHECK: idivl
> +; CHECK: ret
> +}
> +
> +; Has optsize (-Os) attribute, should not generate idiv
> +define i32 @test3(i32 inreg %x) optsize {
> +entry:
> + %div = sdiv i32 %x, 16
> + ret i32 %div
> +; CHECK-LABEL: test3:
> +; CHECK-NOT: idivl
> +; CHECK: ret
> +}
> +
> +
>
>
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