[llvm] eba5f5f - [ValueTracking] Add abs intrinsics support to computeConstantRange()

[Nikita Popov via llvm-commits]

Author: Nikita Popov
Date: 2020-08-12T22:28:46+02:00
New Revision: eba5f5f79823d8fd50f9e1e7f143e3210cc01823

URL: https://github.com/llvm/llvm-project/commit/eba5f5f79823d8fd50f9e1e7f143e3210cc01823
DIFF: https://github.com/llvm/llvm-project/commit/eba5f5f79823d8fd50f9e1e7f143e3210cc01823.diff

LOG: [ValueTracking] Add abs intrinsics support to computeConstantRange()

Implementation is the same as for SPF_ABS.

Added: 
    

Modified: 
    llvm/lib/Analysis/ValueTracking.cpp
    llvm/test/Transforms/InstCombine/abs-intrinsic.ll
    llvm/test/Transforms/InstSimplify/abs_intrinsic.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 5b67eb58fcbd..fa4f4ed37c84 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -6441,6 +6441,14 @@ static void setLimitsForIntrinsic(const IntrinsicInst &II, APInt &Lower,
       llvm_unreachable("Must be min/max intrinsic");
     }
     break;
+  case Intrinsic::abs:
+    // If abs of SIGNED_MIN is poison, then the result is [0..SIGNED_MAX],
+    // otherwise it is [0..SIGNED_MIN], as -SIGNED_MIN == SIGNED_MIN.
+    if (match(II.getOperand(1), m_One()))
+      Upper = APInt::getSignedMaxValue(Width) + 1;
+    else
+      Upper = APInt::getSignedMinValue(Width) + 1;
+    break;
   default:
     break;
   }

diff  --git a/llvm/test/Transforms/InstCombine/abs-intrinsic.ll b/llvm/test/Transforms/InstCombine/abs-intrinsic.ll
index b1d60d5877a5..bf8d2b937d8b 100644
--- a/llvm/test/Transforms/InstCombine/abs-intrinsic.ll
+++ b/llvm/test/Transforms/InstCombine/abs-intrinsic.ll
@@ -63,7 +63,7 @@ define i32 @abs_signbits(i30 %x) {
 ; CHECK-LABEL: @abs_signbits(
 ; CHECK-NEXT:    [[EXT:%.*]] = sext i30 [[X:%.*]] to i32
 ; CHECK-NEXT:    [[ABS:%.*]] = call i32 @llvm.abs.i32(i32 [[EXT]], i1 false)
-; CHECK-NEXT:    [[ADD:%.*]] = add nsw i32 [[ABS]], 1
+; CHECK-NEXT:    [[ADD:%.*]] = add nuw nsw i32 [[ABS]], 1
 ; CHECK-NEXT:    ret i32 [[ADD]]
 ;
   %ext = sext i30 %x to i32
@@ -76,7 +76,7 @@ define <4 x i32> @abs_signbits_vec(<4 x i30> %x) {
 ; CHECK-LABEL: @abs_signbits_vec(
 ; CHECK-NEXT:    [[EXT:%.*]] = sext <4 x i30> [[X:%.*]] to <4 x i32>
 ; CHECK-NEXT:    [[ABS:%.*]] = call <4 x i32> @llvm.abs.v4i32(<4 x i32> [[EXT]], i1 false)
-; CHECK-NEXT:    [[ADD:%.*]] = add nsw <4 x i32> [[ABS]], <i32 1, i32 1, i32 1, i32 1>
+; CHECK-NEXT:    [[ADD:%.*]] = add nuw nsw <4 x i32> [[ABS]], <i32 1, i32 1, i32 1, i32 1>
 ; CHECK-NEXT:    ret <4 x i32> [[ADD]]
 ;
   %ext = sext <4 x i30> %x to <4 x i32>

diff  --git a/llvm/test/Transforms/InstSimplify/abs_intrinsic.ll b/llvm/test/Transforms/InstSimplify/abs_intrinsic.ll
index 0fa2176038ea..aa299c1084b7 100644
--- a/llvm/test/Transforms/InstSimplify/abs_intrinsic.ll
+++ b/llvm/test/Transforms/InstSimplify/abs_intrinsic.ll
@@ -186,9 +186,7 @@ define <4 x i1> @abs_known_not_int_min_vec(<4 x i32> %x) {
 ; If it's >= 0 it should be >= -1 as well.
 define i1 @abs_nsw_sge_neg(i32 %x) {
 ; CHECK-LABEL: @abs_nsw_sge_neg(
-; CHECK-NEXT:    [[ABS:%.*]] = call i32 @llvm.abs.i32(i32 [[X:%.*]], i1 true)
-; CHECK-NEXT:    [[C:%.*]] = icmp sge i32 [[ABS]], -1
-; CHECK-NEXT:    ret i1 [[C]]
+; CHECK-NEXT:    ret i1 true
 ;
   %abs = call i32 @llvm.abs.i32(i32 %x, i1 true)
   %c = icmp sge i32 %abs, -1
@@ -197,9 +195,7 @@ define i1 @abs_nsw_sge_neg(i32 %x) {
 
 define i1 @abs_ule_int_min(i8 %x) {
 ; CHECK-LABEL: @abs_ule_int_min(
-; CHECK-NEXT:    [[ABS:%.*]] = call i8 @llvm.abs.i8(i8 [[X:%.*]], i1 false)
-; CHECK-NEXT:    [[C:%.*]] = icmp ule i8 [[ABS]], -128
-; CHECK-NEXT:    ret i1 [[C]]
+; CHECK-NEXT:    ret i1 true
 ;
   %abs = call i8 @llvm.abs.i8(i8 %x, i1 false)
   %c = icmp ule i8 %abs, 128