[llvm] r209568 - Implement sext(C1 + C2*X) --> sext(C1) + sext(C2*X) and
Benjamin Kramer
benny.kra at gmail.com
Sat May 24 06:59:30 PDT 2014
On 24.05.2014, at 10:09, Michael Zolotukhin <mzolotukhin at apple.com> wrote:
> Author: mzolotukhin
> Date: Sat May 24 03:09:57 2014
> New Revision: 209568
>
> URL: http://llvm.org/viewvc/llvm-project?rev=209568&view=rev
> Log:
> Implement sext(C1 + C2*X) --> sext(C1) + sext(C2*X) and
> sext{C1,+,C2} --> sext(C1) + sext{0,+,C2} transformation in Scalar
> Evolution.
>
> That helps SLP-vectorizer to recognize consecutive loads/stores.
>
> <rdar://problem/14860614>
>
> Added:
> llvm/trunk/test/Transforms/SLPVectorizer/X86/consecutive-access.ll
> Modified:
> llvm/trunk/lib/Analysis/ScalarEvolution.cpp
>
> Modified: llvm/trunk/lib/Analysis/ScalarEvolution.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=209568&r1=209567&r2=209568&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)
> +++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Sat May 24 03:09:57 2014
> @@ -1201,6 +1201,24 @@ const SCEV *ScalarEvolution::getSignExte
> return getTruncateOrSignExtend(X, Ty);
> }
>
> + // sext(C1 + (C2 * x)) --> C1 + sext(C2 * x) if C1 < C2
> + if (auto SA = dyn_cast<SCEVAddExpr>(Op)) {
> + if (SA->getNumOperands() == 2) {
> + auto SC1 = dyn_cast<SCEVConstant>(SA->getOperand(0));
> + auto SMul = dyn_cast<SCEVMulExpr>(SA->getOperand(1));
> + if (SMul && SC1) {
> + if (auto SC2 = dyn_cast<SCEVConstant>(SMul->getOperand(0))) {
> + APInt C1 = SC1->getValue()->getValue();
> + APInt C2 = SC2->getValue()->getValue();
const APInt & can avoid a potentially expensive copy of the APInt.
> + APInt CDiff = C2 - C1;
> + if (C1.isStrictlyPositive() && C2.isStrictlyPositive() &&
> + CDiff.isStrictlyPositive() && C2.isPowerOf2())
Why not C1.ult(C2) instead of comparing the subtracted result?
> + return getAddExpr(getSignExtendExpr(SC1, Ty),
> + getSignExtendExpr(SMul, Ty));
> + }
> + }
> + }
> + }
> // If the input value is a chrec scev, and we can prove that the value
> // did not overflow the old, smaller, value, we can sign extend all of the
> // operands (often constants). This allows analysis of something like
> @@ -1292,6 +1310,23 @@ const SCEV *ScalarEvolution::getSignExte
> L, AR->getNoWrapFlags());
> }
> }
> + // If Start and Step are constants, check if we can apply this
> + // transformation:
> + // sext{C1,+,C2} --> C1 + sext{0,+,C2} if C1 < C2
> + auto SC1 = dyn_cast<SCEVConstant>(Start);
> + auto SC2 = dyn_cast<SCEVConstant>(Step);
> + if (SC1 && SC2) {
> + APInt C1 = SC1->getValue()->getValue();
> + APInt C2 = SC2->getValue()->getValue();
> + APInt CDiff = C2 - C1;
same here.
> + if (C1.isStrictlyPositive() && C2.isStrictlyPositive() &&
> + CDiff.isStrictlyPositive() && C2.isPowerOf2()) {
> + Start = getSignExtendExpr(Start, Ty);
> + const SCEV *NewAR = getAddRecExpr(getConstant(AR->getType(), 0), Step,
> + L, AR->getNoWrapFlags());
> + return getAddExpr(Start, getSignExtendExpr(NewAR, Ty));
> + }
> + }
> }
>
> // The cast wasn't folded; create an explicit cast node.
>
> Added: llvm/trunk/test/Transforms/SLPVectorizer/X86/consecutive-access.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SLPVectorizer/X86/consecutive-access.ll?rev=209568&view=auto
> ==============================================================================
> --- llvm/trunk/test/Transforms/SLPVectorizer/X86/consecutive-access.ll (added)
> +++ llvm/trunk/test/Transforms/SLPVectorizer/X86/consecutive-access.ll Sat May 24 03:09:57 2014
> @@ -0,0 +1,175 @@
> +; RUN: opt < %s -basicaa -slp-vectorizer -S | FileCheck %s
> +target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
> +target triple = "x86_64-apple-macosx10.9.0"
> +
> + at A = common global [2000 x double] zeroinitializer, align 16
> + at B = common global [2000 x double] zeroinitializer, align 16
> + at C = common global [2000 x float] zeroinitializer, align 16
> + at D = common global [2000 x float] zeroinitializer, align 16
> +
> +; Currently SCEV isn't smart enough to figure out that accesses
> +; A[3*i], A[3*i+1] and A[3*i+2] are consecutive, but in future
> +; that would hopefully be fixed. For now, check that this isn't
> +; vectorized.
> +; CHECK-LABEL: foo_3double
> +; CHECK-NOT: x double>
> +; Function Attrs: nounwind ssp uwtable
> +define void @foo_3double(i32 %u) #0 {
> +entry:
> + %u.addr = alloca i32, align 4
> + store i32 %u, i32* %u.addr, align 4
> + %mul = mul nsw i32 %u, 3
> + %idxprom = sext i32 %mul to i64
> + %arrayidx = getelementptr inbounds [2000 x double]* @A, i32 0, i64 %idxprom
> + %0 = load double* %arrayidx, align 8
> + %arrayidx4 = getelementptr inbounds [2000 x double]* @B, i32 0, i64 %idxprom
> + %1 = load double* %arrayidx4, align 8
> + %add5 = fadd double %0, %1
> + store double %add5, double* %arrayidx, align 8
> + %add11 = add nsw i32 %mul, 1
> + %idxprom12 = sext i32 %add11 to i64
> + %arrayidx13 = getelementptr inbounds [2000 x double]* @A, i32 0, i64 %idxprom12
> + %2 = load double* %arrayidx13, align 8
> + %arrayidx17 = getelementptr inbounds [2000 x double]* @B, i32 0, i64 %idxprom12
> + %3 = load double* %arrayidx17, align 8
> + %add18 = fadd double %2, %3
> + store double %add18, double* %arrayidx13, align 8
> + %add24 = add nsw i32 %mul, 2
> + %idxprom25 = sext i32 %add24 to i64
> + %arrayidx26 = getelementptr inbounds [2000 x double]* @A, i32 0, i64 %idxprom25
> + %4 = load double* %arrayidx26, align 8
> + %arrayidx30 = getelementptr inbounds [2000 x double]* @B, i32 0, i64 %idxprom25
> + %5 = load double* %arrayidx30, align 8
> + %add31 = fadd double %4, %5
> + store double %add31, double* %arrayidx26, align 8
> + ret void
> +}
> +
> +; SCEV should be able to tell that accesses A[C1 + C2*i], A[C1 + C2*i], ...
> +; A[C1 + C2*i] are consecutive, if C2 is a power of 2, and C2 > C1 > 0.
> +; Thus, the following code should be vectorized.
> +; CHECK-LABEL: foo_2double
> +; CHECK: x double>
> +; Function Attrs: nounwind ssp uwtable
> +define void @foo_2double(i32 %u) #0 {
> +entry:
> + %u.addr = alloca i32, align 4
> + store i32 %u, i32* %u.addr, align 4
> + %mul = mul nsw i32 %u, 2
> + %idxprom = sext i32 %mul to i64
> + %arrayidx = getelementptr inbounds [2000 x double]* @A, i32 0, i64 %idxprom
> + %0 = load double* %arrayidx, align 8
> + %arrayidx4 = getelementptr inbounds [2000 x double]* @B, i32 0, i64 %idxprom
> + %1 = load double* %arrayidx4, align 8
> + %add5 = fadd double %0, %1
> + store double %add5, double* %arrayidx, align 8
> + %add11 = add nsw i32 %mul, 1
> + %idxprom12 = sext i32 %add11 to i64
> + %arrayidx13 = getelementptr inbounds [2000 x double]* @A, i32 0, i64 %idxprom12
> + %2 = load double* %arrayidx13, align 8
> + %arrayidx17 = getelementptr inbounds [2000 x double]* @B, i32 0, i64 %idxprom12
> + %3 = load double* %arrayidx17, align 8
> + %add18 = fadd double %2, %3
> + store double %add18, double* %arrayidx13, align 8
> + ret void
> +}
> +
> +; Similar to the previous test, but with different datatype.
> +; CHECK-LABEL: foo_4float
> +; CHECK: x float>
> +; Function Attrs: nounwind ssp uwtable
> +define void @foo_4float(i32 %u) #0 {
> +entry:
> + %u.addr = alloca i32, align 4
> + store i32 %u, i32* %u.addr, align 4
> + %mul = mul nsw i32 %u, 4
> + %idxprom = sext i32 %mul to i64
> + %arrayidx = getelementptr inbounds [2000 x float]* @C, i32 0, i64 %idxprom
> + %0 = load float* %arrayidx, align 4
> + %arrayidx4 = getelementptr inbounds [2000 x float]* @D, i32 0, i64 %idxprom
> + %1 = load float* %arrayidx4, align 4
> + %add5 = fadd float %0, %1
> + store float %add5, float* %arrayidx, align 4
> + %add11 = add nsw i32 %mul, 1
> + %idxprom12 = sext i32 %add11 to i64
> + %arrayidx13 = getelementptr inbounds [2000 x float]* @C, i32 0, i64 %idxprom12
> + %2 = load float* %arrayidx13, align 4
> + %arrayidx17 = getelementptr inbounds [2000 x float]* @D, i32 0, i64 %idxprom12
> + %3 = load float* %arrayidx17, align 4
> + %add18 = fadd float %2, %3
> + store float %add18, float* %arrayidx13, align 4
> + %add24 = add nsw i32 %mul, 2
> + %idxprom25 = sext i32 %add24 to i64
> + %arrayidx26 = getelementptr inbounds [2000 x float]* @C, i32 0, i64 %idxprom25
> + %4 = load float* %arrayidx26, align 4
> + %arrayidx30 = getelementptr inbounds [2000 x float]* @D, i32 0, i64 %idxprom25
> + %5 = load float* %arrayidx30, align 4
> + %add31 = fadd float %4, %5
> + store float %add31, float* %arrayidx26, align 4
> + %add37 = add nsw i32 %mul, 3
> + %idxprom38 = sext i32 %add37 to i64
> + %arrayidx39 = getelementptr inbounds [2000 x float]* @C, i32 0, i64 %idxprom38
> + %6 = load float* %arrayidx39, align 4
> + %arrayidx43 = getelementptr inbounds [2000 x float]* @D, i32 0, i64 %idxprom38
> + %7 = load float* %arrayidx43, align 4
> + %add44 = fadd float %6, %7
> + store float %add44, float* %arrayidx39, align 4
> + ret void
> +}
> +
> +; Similar to the previous tests, but now we are dealing with AddRec SCEV.
> +; CHECK-LABEL: foo_loop
> +; CHECK: x double>
> +; Function Attrs: nounwind ssp uwtable
> +define i32 @foo_loop(double* %A, i32 %n) #0 {
> +entry:
> + %A.addr = alloca double*, align 8
> + %n.addr = alloca i32, align 4
> + %sum = alloca double, align 8
> + %i = alloca i32, align 4
> + store double* %A, double** %A.addr, align 8
> + store i32 %n, i32* %n.addr, align 4
> + store double 0.000000e+00, double* %sum, align 8
> + store i32 0, i32* %i, align 4
> + %cmp1 = icmp slt i32 0, %n
> + br i1 %cmp1, label %for.body.lr.ph, label %for.end
> +
> +for.body.lr.ph: ; preds = %entry
> + br label %for.body
> +
> +for.body: ; preds = %for.body.lr.ph, %for.body
> + %0 = phi i32 [ 0, %for.body.lr.ph ], [ %inc, %for.body ]
> + %1 = phi double [ 0.000000e+00, %for.body.lr.ph ], [ %add7, %for.body ]
> + %mul = mul nsw i32 %0, 2
> + %idxprom = sext i32 %mul to i64
> + %arrayidx = getelementptr inbounds double* %A, i64 %idxprom
> + %2 = load double* %arrayidx, align 8
> + %mul1 = fmul double 7.000000e+00, %2
> + %add = add nsw i32 %mul, 1
> + %idxprom3 = sext i32 %add to i64
> + %arrayidx4 = getelementptr inbounds double* %A, i64 %idxprom3
> + %3 = load double* %arrayidx4, align 8
> + %mul5 = fmul double 7.000000e+00, %3
> + %add6 = fadd double %mul1, %mul5
> + %add7 = fadd double %1, %add6
> + store double %add7, double* %sum, align 8
> + %inc = add nsw i32 %0, 1
> + store i32 %inc, i32* %i, align 4
> + %cmp = icmp slt i32 %inc, %n
> + br i1 %cmp, label %for.body, label %for.cond.for.end_crit_edge
> +
> +for.cond.for.end_crit_edge: ; preds = %for.body
> + %split = phi double [ %add7, %for.body ]
> + br label %for.end
> +
> +for.end: ; preds = %for.cond.for.end_crit_edge, %entry
> + %.lcssa = phi double [ %split, %for.cond.for.end_crit_edge ], [ 0.000000e+00, %entry ]
> + %conv = fptosi double %.lcssa to i32
> + ret i32 %conv
> +}
> +
> +attributes #0 = { nounwind ssp uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
> +
> +!llvm.ident = !{!0}
> +
> +!0 = metadata !{metadata !"clang version 3.5.0 "}
>
>
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