[SCEV] Support SCEVUMinExpr in getRangeRef.

[fhahn]

Summary

This patch adds support for SCEVUMinExpr to getRangeRef,
similar to the support for SCEVUMaxExpr.

[sanjoy.google]

lgtm

llvm/trunk/lib/Analysis/ScalarEvolution.cpp

ScalarEvolution::getRangeRef(const SCEV *S,
   if (const SCEVUMaxExpr *UMax = dyn_cast<SCEVUMaxExpr>(S)) {
     ConstantRange X = getRangeRef(UMax->getOperand(0), SignHint);
     for (unsigned i = 1, e = UMax->getNumOperands(); i != e; ++i)
       X = X.umax(getRangeRef(UMax->getOperand(i), SignHint));
     return setRange(UMax, SignHint,
                     ConservativeResult.intersectWith(X, RangeType));
   }
 
+  if (const SCEVUMinExpr *UMin = dyn_cast<SCEVUMinExpr>(S)) {
+    ConstantRange X = getRangeRef(UMin->getOperand(0), SignHint);
+    for (unsigned i = 1, e = UMin->getNumOperands(); i != e; ++i)
+      X = X.umin(getRangeRef(UMin->getOperand(i), SignHint));
+    return setRange(UMin, SignHint,
+                    ConservativeResult.intersectWith(X, RangeType));
+  }
+
   if (const SCEVUDivExpr *UDiv = dyn_cast<SCEVUDivExpr>(S)) {
     ConstantRange X = getRangeRef(UDiv->getLHS(), SignHint);
     ConstantRange Y = getRangeRef(UDiv->getRHS(), SignHint);
     return setRange(UDiv, SignHint,
                     ConservativeResult.intersectWith(X.udiv(Y), RangeType));
   }
 
   if (const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(S)) {

llvm/trunk/test/Analysis/ScalarEvolution/max-expr-cache.ll

bb4:
   %tmp40 = select i1 %tmp39, i32 %tmp38, i32 256
   %tmp41 = add nsw i32 %tmp40, 1
   %tmp42 = icmp ugt i32 %tmp8, %tmp41
   %tmp43 = select i1 %tmp42, i32 %tmp41, i32 %tmp8
   %tmp44 = add nsw i32 %tmp10, 7
   %tmp45 = icmp ult i32 %tmp43, 256
   %tmp46 = select i1 %tmp45, i32 %tmp43, i32 256
 ; CHECK:  %tmp46 = select i1 %tmp45, i32 %tmp43, i32 256
-; CHECK-NEXT:  --> (256 umin (1 + (256 umin (1 + (256 umin (1 + (256 umin (1 + (256 umin (1 + (256 umin (1 + (256 umin (1 + (256 umin {%tmp3,+,-256}<%bb4>)) umin {%tmp3,+,-256}<%bb4>)) umin {%tmp3,+,-256}<%bb4>)) umin {%tmp3,+,-256}<%bb4>)) umin {%tmp3,+,-256}<%bb4>)) umin {%tmp3,+,-256}<%bb4>)) umin {%tmp3,+,-256}<%bb4>)) umin {%tmp3,+,-256}<%bb4>) 
+; CHECK-NEXT:  -->  (256 umin (1 + (256 umin (1 + (256 umin (1 + (256 umin (1 + (256 umin (1 + (256 umin (1 + (256 umin (1 + (256 umin {%tmp3,+,-256}<%bb4>))<nuw><nsw> umin {%tmp3,+,-256}<%bb4>))<nuw><nsw> umin {%tmp3,+,-256}<%bb4>))<nuw><nsw> umin {%tmp3,+,-256}<%bb4>))<nuw><nsw> umin {%tmp3,+,-256}<%bb4>))<nuw><nsw> umin {%tmp3,+,-256}<%bb4>))<nuw><nsw> umin {%tmp3,+,-256}<%bb4>))<nuw><nsw> umin {%tmp3,+,-256}<%bb4>) U: [0,257) S: [0,257) Exits: <<Unknown>> LoopDispositions: { %bb4: Computable, %bb53: Invariant }
   %tmp47 = icmp ugt i32 %tmp44, %tmp46
   %tmp48 = select i1 %tmp47, i32 %tmp44, i32 %tmp46
   %tmp49 = ashr i32 %tmp48, 3
   %tmp50 = icmp ugt i32 %tmp49, 0
   %tmp51 = select i1 %tmp50, i32 %tmp49, i32 0
   %tmp52 = zext i32 %tmp51 to i64
   br label %bb53
 

llvm/trunk/test/Analysis/ScalarEvolution/trip-count15.ll

 ; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py
 ; RUN: opt -S -analyze -scalar-evolution < %s | FileCheck %s
 
 define void @umin_unsigned_check(i64 %n) {
 ; CHECK-LABEL: 'umin_unsigned_check'
 ; CHECK-NEXT:  Classifying expressions for: @umin_unsigned_check
 ; CHECK-NEXT:    %min.n = select i1 %min.cmp, i64 4096, i64 %n
-; CHECK-NEXT:    --> (4096 umin %n) U: full-set S: full-set
+; CHECK-NEXT:    --> (4096 umin %n) U: [0,4097) S: [0,4097)
 ; CHECK-NEXT:    %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
-; CHECK-NEXT:    --> {0,+,1}<%loop> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT:    --> {0,+,1}<%loop> U: [0,4098) S: [0,4098) Exits: (1 + (4096 umin %n))<nuw><nsw> LoopDispositions: { %loop: Computable }
 ; CHECK-NEXT:    %iv.next = add i64 %iv, 1
-; CHECK-NEXT:    --> {1,+,1}<%loop> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT:    --> {1,+,1}<%loop> U: [1,4099) S: [1,4099) Exits: (2 + (4096 umin %n)) LoopDispositions: { %loop: Computable }
 ; CHECK-NEXT:  Determining loop execution counts for: @umin_unsigned_check
-; CHECK-NEXT:  Loop %loop: Unpredictable backedge-taken count.
-; CHECK-NEXT:  Loop %loop: Unpredictable max backedge-taken count.
-; CHECK-NEXT:  Loop %loop: Unpredictable predicated backedge-taken count.
+; CHECK-NEXT:  Loop %loop: backedge-taken count is (1 + (4096 umin %n))<nuw><nsw>
+; CHECK-NEXT:  Loop %loop: max backedge-taken count is 4097
+; CHECK-NEXT:  Loop %loop: Predicated backedge-taken count is (1 + (4096 umin %n))<nuw><nsw>
 ;
 entry:
   %min.cmp = icmp ult i64 4096, %n
   %min.n = select i1 %min.cmp, i64 4096, i64 %n
   br label %loop
 loop:
   %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
   %iv.next = add i64 %iv, 1
   %exit = icmp ugt i64 %iv, %min.n
   br i1 %exit, label %loop_exit, label %loop
 
 loop_exit:
   ret void
 }
 
 define void @umin_signed_check(i64 %n) {
 ; CHECK-LABEL: 'umin_signed_check'
 ; CHECK-NEXT:  Classifying expressions for: @umin_signed_check
 ; CHECK-NEXT:    %min.n = select i1 %min.cmp, i64 4096, i64 %n
-; CHECK-NEXT:    --> (4096 umin %n) U: full-set S: full-set
+; CHECK-NEXT:    --> (4096 umin %n) U: [0,4097) S: [0,4097)
 ; CHECK-NEXT:    %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
-; CHECK-NEXT:    --> {0,+,1}<%loop> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT:    --> {0,+,1}<%loop> U: [0,4098) S: [0,4098) Exits: (1 + (4096 umin %n))<nuw><nsw> LoopDispositions: { %loop: Computable }
 ; CHECK-NEXT:    %iv.next = add i64 %iv, 1
-; CHECK-NEXT:    --> {1,+,1}<%loop> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT:    --> {1,+,1}<%loop> U: [1,4099) S: [1,4099) Exits: (2 + (4096 umin %n)) LoopDispositions: { %loop: Computable }
 ; CHECK-NEXT:  Determining loop execution counts for: @umin_signed_check
-; CHECK-NEXT:  Loop %loop: Unpredictable backedge-taken count.
-; CHECK-NEXT:  Loop %loop: Unpredictable max backedge-taken count.
-; CHECK-NEXT:  Loop %loop: Unpredictable predicated backedge-taken count.
+; CHECK-NEXT:  Loop %loop: backedge-taken count is (1 + (4096 umin %n))<nuw><nsw>
+; CHECK-NEXT:  Loop %loop: max backedge-taken count is 4097
+; CHECK-NEXT:  Loop %loop: Predicated backedge-taken count is (1 + (4096 umin %n))<nuw><nsw>
 ;
 entry:
   %min.cmp = icmp ult i64 4096, %n
   %min.n = select i1 %min.cmp, i64 4096, i64 %n
   br label %loop
 loop:
   %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
   %iv.next = add i64 %iv, 1