From: Sanjay Patel <spatel@rotateright.com>
Date: Tue, 4 Aug 2020 12:28:44 +0000 (-0400)
Subject: [InstSimplify] fold nested min/max intrinsics with constant operands
X-Git-Tag: llvmorg-13-init~15875
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=04e45ae1c6d2fdbf3fd4242df69d1511df757d48;p=platform%2Fupstream%2Fllvm.git

[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) >
---

diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index 2119ddc..6b8f8e3 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 3aa19e91..6b10853 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>)