From e2040d38a1c77b1ff544f96dc6ce31894e3799f0 Mon Sep 17 00:00:00 2001
From: Nikita Popov <nikita.ppv@gmail.com>
Date: Wed, 12 Aug 2020 22:05:56 +0200
Subject: [PATCH] [ValueTracking] Support min/max intrinsics in
 computeConstantRange()

The implementation is the same as for the SPF_* case.
---
 llvm/lib/Analysis/ValueTracking.cpp           | 27 +++++++++++++++++++
 .../InstSimplify/maxmin_intrinsics.ll         | 16 +++--------
 2 files changed, 31 insertions(+), 12 deletions(-)

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 3cd90e8ece75f..5b67eb58fcbdb 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -6414,6 +6414,33 @@ static void setLimitsForIntrinsic(const IntrinsicInst &II, APInt &Lower,
       }
     }
     break;
+  case Intrinsic::umin:
+  case Intrinsic::umax:
+  case Intrinsic::smin:
+  case Intrinsic::smax:
+    if (!match(II.getOperand(0), m_APInt(C)) &&
+        !match(II.getOperand(1), m_APInt(C)))
+      break;
+
+    switch (II.getIntrinsicID()) {
+    case Intrinsic::umin:
+      Upper = *C + 1;
+      break;
+    case Intrinsic::umax:
+      Lower = *C;
+      break;
+    case Intrinsic::smin:
+      Lower = APInt::getSignedMinValue(Width);
+      Upper = *C + 1;
+      break;
+    case Intrinsic::smax:
+      Lower = *C;
+      Upper = APInt::getSignedMaxValue(Width) + 1;
+      break;
+    default:
+      llvm_unreachable("Must be min/max intrinsic");
+    }
+    break;
   default:
     break;
   }
diff --git a/llvm/test/Transforms/InstSimplify/maxmin_intrinsics.ll b/llvm/test/Transforms/InstSimplify/maxmin_intrinsics.ll
index 8bb93d8245b7c..98c6785827aa7 100644
--- a/llvm/test/Transforms/InstSimplify/maxmin_intrinsics.ll
+++ b/llvm/test/Transforms/InstSimplify/maxmin_intrinsics.ll
@@ -1856,9 +1856,7 @@ define i8 @umin_umin_umin(i8 %x, i8 %y) {
 
 define i1 @umin_ult_diff_const(i8 %x) {
 ; CHECK-LABEL: @umin_ult_diff_const(
-; CHECK-NEXT:    [[M:%.*]] = call i8 @llvm.umin.i8(i8 [[X:%.*]], i8 10)
-; CHECK-NEXT:    [[C:%.*]] = icmp ult i8 [[M]], 20
-; CHECK-NEXT:    ret i1 [[C]]
+; CHECK-NEXT:    ret i1 true
 ;
   %m = call i8 @llvm.umin.i8(i8 %x, i8 10)
   %c = icmp ult i8 %m, 20
@@ -1867,9 +1865,7 @@ define i1 @umin_ult_diff_const(i8 %x) {
 
 define i1 @umax_ugt_diff_const(i8 %x) {
 ; CHECK-LABEL: @umax_ugt_diff_const(
-; CHECK-NEXT:    [[M:%.*]] = call i8 @llvm.umax.i8(i8 [[X:%.*]], i8 10)
-; CHECK-NEXT:    [[C:%.*]] = icmp ugt i8 [[M]], 5
-; CHECK-NEXT:    ret i1 [[C]]
+; CHECK-NEXT:    ret i1 true
 ;
   %m = call i8 @llvm.umax.i8(i8 %x, i8 10)
   %c = icmp ugt i8 %m, 5
@@ -1878,9 +1874,7 @@ define i1 @umax_ugt_diff_const(i8 %x) {
 
 define i1 @smin_slt_diff_const(i8 %x) {
 ; CHECK-LABEL: @smin_slt_diff_const(
-; CHECK-NEXT:    [[M:%.*]] = call i8 @llvm.smin.i8(i8 [[X:%.*]], i8 10)
-; CHECK-NEXT:    [[C:%.*]] = icmp slt i8 [[M]], 20
-; CHECK-NEXT:    ret i1 [[C]]
+; CHECK-NEXT:    ret i1 true
 ;
   %m = call i8 @llvm.smin.i8(i8 %x, i8 10)
   %c = icmp slt i8 %m, 20
@@ -1889,9 +1883,7 @@ define i1 @smin_slt_diff_const(i8 %x) {
 
 define i1 @smax_sgt_diff_const(i8 %x) {
 ; CHECK-LABEL: @smax_sgt_diff_const(
-; CHECK-NEXT:    [[M:%.*]] = call i8 @llvm.smax.i8(i8 [[X:%.*]], i8 10)
-; CHECK-NEXT:    [[C:%.*]] = icmp sgt i8 [[M]], 5
-; CHECK-NEXT:    ret i1 [[C]]
+; CHECK-NEXT:    ret i1 true
 ;
   %m = call i8 @llvm.smax.i8(i8 %x, i8 10)
   %c = icmp sgt i8 %m, 5