[llvm] 04e45ae - [InstSimplify] fold nested min/max intrinsics with constant operands
Philip Reames via llvm-commits
llvm-commits at lists.llvm.org
Wed Aug 5 10:26:59 PDT 2020
A thought on a possible generalization.
Instead of restricting this to constants, could we use generic reasoning
about Value relations? If we implement a isKnownPredicate variant, we
could handle cases such as the following:
%b = add nsw %a, 1
%c = smin(%a, %b) ;; %c == %b
Weirdly, I can't find analogous code for selects. I'd have assumed we
handled cases like this...
Philip
On 8/4/20 5:44 AM, Sanjay Patel via llvm-commits wrote:
> Author: Sanjay Patel
> Date: 2020-08-04T08:44:48-04:00
> New Revision: 04e45ae1c6d2fdbf3fd4242df69d1511df757d48
>
> URL: https://github.com/llvm/llvm-project/commit/04e45ae1c6d2fdbf3fd4242df69d1511df757d48
> DIFF: https://github.com/llvm/llvm-project/commit/04e45ae1c6d2fdbf3fd4242df69d1511df757d48.diff
>
> LOG: [InstSimplify] fold nested min/max intrinsics with constant operands
>
> This is based on the existing code for the non-intrinsic idioms
> in InstCombine.
>
> The vector constant constraint is non-obvious: undefs should be
> ok in the outer call, but they can't propagate safely from the
> inner call in all cases. Example:
>
> https://alive2.llvm.org/ce/z/-2bVbM
> define <2 x i8> @src(<2 x i8> %x) {
> %0:
> %m = umin <2 x i8> %x, { 7, undef }
> %m2 = umin <2 x i8> { 9, 9 }, %m
> ret <2 x i8> %m2
> }
> =>
> define <2 x i8> @tgt(<2 x i8> %x) {
> %0:
> %m = umin <2 x i8> %x, { 7, undef }
> ret <2 x i8> %m
> }
> Transformation doesn't verify!
> ERROR: Value mismatch
>
> Example:
> <2 x i8> %x = < undef, undef >
>
> Source:
> <2 x i8> %m = < #x00 (0) [based on undef value], #x00 (0) >
> <2 x i8> %m2 = < #x00 (0), #x00 (0) >
>
> Target:
> <2 x i8> %m = < #x07 (7), #x10 (16) >
> Source value: < #x00 (0), #x00 (0) >
> Target value: < #x07 (7), #x10 (16) >
>
> Added:
>
>
> Modified:
> llvm/lib/Analysis/InstructionSimplify.cpp
> llvm/test/Transforms/InstSimplify/maxmin_intrinsics.ll
>
> Removed:
>
>
>
> ################################################################################
> diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
> index 2119ddcc7649..6b8f8e3acc17 100644
> --- a/llvm/lib/Analysis/InstructionSimplify.cpp
> +++ b/llvm/lib/Analysis/InstructionSimplify.cpp
> @@ -5285,6 +5285,21 @@ static Value *simplifyBinaryIntrinsic(Function *F, Value *Op0, Value *Op1,
> // umin(i8 %x, i8 255) --> %x
> if (*C == getMaxMinLimit(getMaxMinOpposite(IID), BitWidth))
> return Op0;
> +
> + // Remove nested call if constant operands allow it. Example:
> + // max (max X, 7), 5 -> max X, 7
> + auto *MinMax0 = dyn_cast<IntrinsicInst>(Op0);
> + if (MinMax0 && MinMax0->getIntrinsicID() == IID) {
> + // TODO: loosen undef/splat restrictions for vector constants.
> + Value *M00 = MinMax0->getOperand(0), *M01 = MinMax0->getOperand(1);
> + const APInt *InnerC;
> + if ((match(M00, m_APInt(InnerC)) || match(M01, m_APInt(InnerC))) &&
> + ((IID == Intrinsic::smax && InnerC->sge(*C)) ||
> + (IID == Intrinsic::smin && InnerC->sle(*C)) ||
> + (IID == Intrinsic::umax && InnerC->uge(*C)) ||
> + (IID == Intrinsic::umin && InnerC->ule(*C))))
> + return Op0;
> + }
> }
>
> break;
>
> diff --git a/llvm/test/Transforms/InstSimplify/maxmin_intrinsics.ll b/llvm/test/Transforms/InstSimplify/maxmin_intrinsics.ll
> index 3aa19e91e0e3..6b10853dd78f 100644
> --- a/llvm/test/Transforms/InstSimplify/maxmin_intrinsics.ll
> +++ b/llvm/test/Transforms/InstSimplify/maxmin_intrinsics.ll
> @@ -627,8 +627,7 @@ define i8 @umin_smin(i8 %x, i8 %y) {
> define i8 @umax_umax_constants(i8 %x) {
> ; CHECK-LABEL: @umax_umax_constants(
> ; CHECK-NEXT: [[M:%.*]] = call i8 @llvm.umax.i8(i8 [[X:%.*]], i8 9)
> -; CHECK-NEXT: [[M2:%.*]] = call i8 @llvm.umax.i8(i8 7, i8 [[M]])
> -; CHECK-NEXT: ret i8 [[M2]]
> +; CHECK-NEXT: ret i8 [[M]]
> ;
> %m = call i8 @llvm.umax.i8(i8 %x, i8 9)
> %m2 = call i8 @llvm.umax.i8(i8 7, i8 %m)
> @@ -638,8 +637,7 @@ define i8 @umax_umax_constants(i8 %x) {
> define i8 @umax_umax_constants_commute1(i8 %x) {
> ; CHECK-LABEL: @umax_umax_constants_commute1(
> ; CHECK-NEXT: [[M:%.*]] = call i8 @llvm.umax.i8(i8 -128, i8 [[X:%.*]])
> -; CHECK-NEXT: [[M2:%.*]] = call i8 @llvm.umax.i8(i8 7, i8 [[M]])
> -; CHECK-NEXT: ret i8 [[M2]]
> +; CHECK-NEXT: ret i8 [[M]]
> ;
> %m = call i8 @llvm.umax.i8(i8 128, i8 %x)
> %m2 = call i8 @llvm.umax.i8(i8 7, i8 %m)
> @@ -649,8 +647,7 @@ define i8 @umax_umax_constants_commute1(i8 %x) {
> define i8 @umax_umax_constants_commute2(i8 %x) {
> ; CHECK-LABEL: @umax_umax_constants_commute2(
> ; CHECK-NEXT: [[M:%.*]] = call i8 @llvm.umax.i8(i8 [[X:%.*]], i8 -56)
> -; CHECK-NEXT: [[M2:%.*]] = call i8 @llvm.umax.i8(i8 [[M]], i8 127)
> -; CHECK-NEXT: ret i8 [[M2]]
> +; CHECK-NEXT: ret i8 [[M]]
> ;
> %m = call i8 @llvm.umax.i8(i8 %x, i8 200)
> %m2 = call i8 @llvm.umax.i8(i8 %m, i8 127)
> @@ -660,8 +657,7 @@ define i8 @umax_umax_constants_commute2(i8 %x) {
> define <2 x i8> @umax_umax_constants_commute3(<2 x i8> %x) {
> ; CHECK-LABEL: @umax_umax_constants_commute3(
> ; CHECK-NEXT: [[M:%.*]] = call <2 x i8> @llvm.umax.v2i8(<2 x i8> <i8 -2, i8 -2>, <2 x i8> [[X:%.*]])
> -; CHECK-NEXT: [[M2:%.*]] = call <2 x i8> @llvm.umax.v2i8(<2 x i8> [[M]], <2 x i8> <i8 -128, i8 -128>)
> -; CHECK-NEXT: ret <2 x i8> [[M2]]
> +; CHECK-NEXT: ret <2 x i8> [[M]]
> ;
> %m = call <2 x i8> @llvm.umax.v2i8(<2 x i8> <i8 254, i8 254>, <2 x i8> %x)
> %m2 = call <2 x i8> @llvm.umax.v2i8(<2 x i8> %m, <2 x i8> <i8 128, i8 128>)
> @@ -671,8 +667,7 @@ define <2 x i8> @umax_umax_constants_commute3(<2 x i8> %x) {
> define i8 @umin_umin_constants(i8 %x) {
> ; CHECK-LABEL: @umin_umin_constants(
> ; CHECK-NEXT: [[M:%.*]] = call i8 @llvm.umin.i8(i8 [[X:%.*]], i8 7)
> -; CHECK-NEXT: [[M2:%.*]] = call i8 @llvm.umin.i8(i8 9, i8 [[M]])
> -; CHECK-NEXT: ret i8 [[M2]]
> +; CHECK-NEXT: ret i8 [[M]]
> ;
> %m = call i8 @llvm.umin.i8(i8 %x, i8 7)
> %m2 = call i8 @llvm.umin.i8(i8 9, i8 %m)
> @@ -682,8 +677,7 @@ define i8 @umin_umin_constants(i8 %x) {
> define i8 @umin_umin_constants_commute1(i8 %x) {
> ; CHECK-LABEL: @umin_umin_constants_commute1(
> ; CHECK-NEXT: [[M:%.*]] = call i8 @llvm.umin.i8(i8 7, i8 [[X:%.*]])
> -; CHECK-NEXT: [[M2:%.*]] = call i8 @llvm.umin.i8(i8 -128, i8 [[M]])
> -; CHECK-NEXT: ret i8 [[M2]]
> +; CHECK-NEXT: ret i8 [[M]]
> ;
> %m = call i8 @llvm.umin.i8(i8 7, i8 %x)
> %m2 = call i8 @llvm.umin.i8(i8 128, i8 %m)
> @@ -693,8 +687,7 @@ define i8 @umin_umin_constants_commute1(i8 %x) {
> define <2 x i8> @umin_umin_constants_commute2(<2 x i8> %x) {
> ; CHECK-LABEL: @umin_umin_constants_commute2(
> ; CHECK-NEXT: [[M:%.*]] = call <2 x i8> @llvm.umin.v2i8(<2 x i8> [[X:%.*]], <2 x i8> <i8 127, i8 127>)
> -; CHECK-NEXT: [[M2:%.*]] = call <2 x i8> @llvm.umin.v2i8(<2 x i8> [[M]], <2 x i8> <i8 -56, i8 undef>)
> -; CHECK-NEXT: ret <2 x i8> [[M2]]
> +; CHECK-NEXT: ret <2 x i8> [[M]]
> ;
> %m = call <2 x i8> @llvm.umin.v2i8(<2 x i8> %x, <2 x i8> <i8 127, i8 127>)
> %m2 = call <2 x i8> @llvm.umin.v2i8(<2 x i8> %m, <2 x i8> <i8 200, i8 undef>)
> @@ -704,8 +697,7 @@ define <2 x i8> @umin_umin_constants_commute2(<2 x i8> %x) {
> define i8 @umin_umin_constants_commute3(i8 %x) {
> ; CHECK-LABEL: @umin_umin_constants_commute3(
> ; CHECK-NEXT: [[M:%.*]] = call i8 @llvm.umin.i8(i8 -128, i8 [[X:%.*]])
> -; CHECK-NEXT: [[M2:%.*]] = call i8 @llvm.umin.i8(i8 [[M]], i8 -2)
> -; CHECK-NEXT: ret i8 [[M2]]
> +; CHECK-NEXT: ret i8 [[M]]
> ;
> %m = call i8 @llvm.umin.i8(i8 128, i8 %x)
> %m2 = call i8 @llvm.umin.i8(i8 %m, i8 254)
> @@ -715,8 +707,7 @@ define i8 @umin_umin_constants_commute3(i8 %x) {
> define i8 @smax_smax_constants(i8 %x) {
> ; CHECK-LABEL: @smax_smax_constants(
> ; CHECK-NEXT: [[M:%.*]] = call i8 @llvm.smax.i8(i8 [[X:%.*]], i8 9)
> -; CHECK-NEXT: [[M2:%.*]] = call i8 @llvm.smax.i8(i8 7, i8 [[M]])
> -; CHECK-NEXT: ret i8 [[M2]]
> +; CHECK-NEXT: ret i8 [[M]]
> ;
> %m = call i8 @llvm.smax.i8(i8 %x, i8 9)
> %m2 = call i8 @llvm.smax.i8(i8 7, i8 %m)
> @@ -726,8 +717,7 @@ define i8 @smax_smax_constants(i8 %x) {
> define <2 x i8> @smax_smax_constants_commute1(<2 x i8> %x) {
> ; CHECK-LABEL: @smax_smax_constants_commute1(
> ; CHECK-NEXT: [[M:%.*]] = call <2 x i8> @llvm.smax.v2i8(<2 x i8> <i8 7, i8 7>, <2 x i8> [[X:%.*]])
> -; CHECK-NEXT: [[M2:%.*]] = call <2 x i8> @llvm.smax.v2i8(<2 x i8> <i8 -127, i8 -127>, <2 x i8> [[M]])
> -; CHECK-NEXT: ret <2 x i8> [[M2]]
> +; CHECK-NEXT: ret <2 x i8> [[M]]
> ;
> %m = call <2 x i8> @llvm.smax.v2i8(<2 x i8> <i8 7, i8 7>, <2 x i8> %x)
> %m2 = call <2 x i8> @llvm.smax.v2i8(<2 x i8> <i8 -127, i8 -127>, <2 x i8> %m)
> @@ -737,8 +727,7 @@ define <2 x i8> @smax_smax_constants_commute1(<2 x i8> %x) {
> define i8 @smax_smax_constants_commute2(i8 %x) {
> ; CHECK-LABEL: @smax_smax_constants_commute2(
> ; CHECK-NEXT: [[M:%.*]] = call i8 @llvm.smax.i8(i8 [[X:%.*]], i8 0)
> -; CHECK-NEXT: [[M2:%.*]] = call i8 @llvm.smax.i8(i8 [[M]], i8 -1)
> -; CHECK-NEXT: ret i8 [[M2]]
> +; CHECK-NEXT: ret i8 [[M]]
> ;
> %m = call i8 @llvm.smax.i8(i8 %x, i8 0)
> %m2 = call i8 @llvm.smax.i8(i8 %m, i8 -1)
> @@ -748,8 +737,7 @@ define i8 @smax_smax_constants_commute2(i8 %x) {
> define i8 @smax_smax_constants_commute3(i8 %x) {
> ; CHECK-LABEL: @smax_smax_constants_commute3(
> ; CHECK-NEXT: [[M:%.*]] = call i8 @llvm.smax.i8(i8 -1, i8 [[X:%.*]])
> -; CHECK-NEXT: [[M2:%.*]] = call i8 @llvm.smax.i8(i8 [[M]], i8 -127)
> -; CHECK-NEXT: ret i8 [[M2]]
> +; CHECK-NEXT: ret i8 [[M]]
> ;
> %m = call i8 @llvm.smax.i8(i8 -1, i8 %x)
> %m2 = call i8 @llvm.smax.i8(i8 %m, i8 -127)
> @@ -759,8 +747,7 @@ define i8 @smax_smax_constants_commute3(i8 %x) {
> define <2 x i8> @smin_smin_constants(<2 x i8> %x) {
> ; CHECK-LABEL: @smin_smin_constants(
> ; CHECK-NEXT: [[M:%.*]] = call <2 x i8> @llvm.smin.v2i8(<2 x i8> [[X:%.*]], <2 x i8> <i8 7, i8 7>)
> -; CHECK-NEXT: [[M2:%.*]] = call <2 x i8> @llvm.smin.v2i8(<2 x i8> <i8 undef, i8 9>, <2 x i8> [[M]])
> -; CHECK-NEXT: ret <2 x i8> [[M2]]
> +; CHECK-NEXT: ret <2 x i8> [[M]]
> ;
> %m = call <2 x i8> @llvm.smin.v2i8(<2 x i8> %x, <2 x i8> <i8 7, i8 7>)
> %m2 = call <2 x i8> @llvm.smin.v2i8(<2 x i8> <i8 undef, i8 9>, <2 x i8> %m)
> @@ -770,8 +757,7 @@ define <2 x i8> @smin_smin_constants(<2 x i8> %x) {
> define i8 @smin_smin_constants_commute1(i8 %x) {
> ; CHECK-LABEL: @smin_smin_constants_commute1(
> ; CHECK-NEXT: [[M:%.*]] = call i8 @llvm.smin.i8(i8 -127, i8 [[X:%.*]])
> -; CHECK-NEXT: [[M2:%.*]] = call i8 @llvm.smin.i8(i8 7, i8 [[M]])
> -; CHECK-NEXT: ret i8 [[M2]]
> +; CHECK-NEXT: ret i8 [[M]]
> ;
> %m = call i8 @llvm.smin.i8(i8 -127, i8 %x)
> %m2 = call i8 @llvm.smin.i8(i8 7, i8 %m)
> @@ -781,8 +767,7 @@ define i8 @smin_smin_constants_commute1(i8 %x) {
> define i8 @smin_smin_constants_commute2(i8 %x) {
> ; CHECK-LABEL: @smin_smin_constants_commute2(
> ; CHECK-NEXT: [[M:%.*]] = call i8 @llvm.smin.i8(i8 [[X:%.*]], i8 -1)
> -; CHECK-NEXT: [[M2:%.*]] = call i8 @llvm.smin.i8(i8 [[M]], i8 0)
> -; CHECK-NEXT: ret i8 [[M2]]
> +; CHECK-NEXT: ret i8 [[M]]
> ;
> %m = call i8 @llvm.smin.i8(i8 %x, i8 -1)
> %m2 = call i8 @llvm.smin.i8(i8 %m, i8 0)
> @@ -792,14 +777,15 @@ define i8 @smin_smin_constants_commute2(i8 %x) {
> define i8 @smin_smin_constants_commute3(i8 %x) {
> ; CHECK-LABEL: @smin_smin_constants_commute3(
> ; CHECK-NEXT: [[M:%.*]] = call i8 @llvm.smin.i8(i8 -127, i8 [[X:%.*]])
> -; CHECK-NEXT: [[M2:%.*]] = call i8 @llvm.smin.i8(i8 [[M]], i8 -1)
> -; CHECK-NEXT: ret i8 [[M2]]
> +; CHECK-NEXT: ret i8 [[M]]
> ;
> %m = call i8 @llvm.smin.i8(i8 -127, i8 %x)
> %m2 = call i8 @llvm.smin.i8(i8 %m, i8 -1)
> ret i8 %m2
> }
>
> +; Negative test - undef in inner constant must not propagate.
> +
> define <2 x i8> @umin_umin_constants_partial_undef(<2 x i8> %x) {
> ; CHECK-LABEL: @umin_umin_constants_partial_undef(
> ; CHECK-NEXT: [[M:%.*]] = call <2 x i8> @llvm.umin.v2i8(<2 x i8> [[X:%.*]], <2 x i8> <i8 7, i8 undef>)
> @@ -811,6 +797,8 @@ define <2 x i8> @umin_umin_constants_partial_undef(<2 x i8> %x) {
> ret <2 x i8> %m2
> }
>
> +; Negative test - undef in inner constant must not propagate.
> +
> define <2 x i8> @smax_smax_constants_partial_undef(<2 x i8> %x) {
> ; CHECK-LABEL: @smax_smax_constants_partial_undef(
> ; CHECK-NEXT: [[M:%.*]] = call <2 x i8> @llvm.smax.v2i8(<2 x i8> [[X:%.*]], <2 x i8> <i8 undef, i8 10>)
>
>
>
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