[llvm] r371776 - [SCEV] Add smin support to getRangeRef

Philip Reames via llvm-commits llvm-commits at lists.llvm.org
Thu Sep 12 14:32:27 PDT 2019 

Author: reames
Date: Thu Sep 12 14:32:27 2019
New Revision: 371776

URL: http://llvm.org/viewvc/llvm-project?rev=371776&view=rev
Log:
[SCEV] Add smin support to getRangeRef

We were failing to compute trip counts (both exact and maximum) for any loop which involved a comparison against either an umin or smin. It looks like this simply got missed when we added smin/umin to SCEV.  (Note: umin was submitted separately earlier today.  Turned out two folks hit this at the same time.)

Differential Revision: https://reviews.llvm.org/D67514


Modified:
    llvm/trunk/lib/Analysis/ScalarEvolution.cpp
    llvm/trunk/test/Analysis/ScalarEvolution/max-expr-cache.ll
    llvm/trunk/test/Analysis/ScalarEvolution/trip-count15.ll
    llvm/trunk/test/Transforms/IRCE/rc-negative-bound.ll

Modified: llvm/trunk/lib/Analysis/ScalarEvolution.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=371776&r1=371775&r2=371776&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)
+++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Thu Sep 12 14:32:27 2019
@@ -5596,6 +5596,14 @@ ScalarEvolution::getRangeRef(const SCEV
                     ConservativeResult.intersectWith(X, RangeType));
   }
 
+  if (const SCEVSMinExpr *SMin = dyn_cast<SCEVSMinExpr>(S)) {
+    ConstantRange X = getRangeRef(SMin->getOperand(0), SignHint);
+    for (unsigned i = 1, e = SMin->getNumOperands(); i != e; ++i)
+      X = X.smin(getRangeRef(SMin->getOperand(i), SignHint));
+    return setRange(SMin, 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)

Modified: llvm/trunk/test/Analysis/ScalarEvolution/max-expr-cache.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/ScalarEvolution/max-expr-cache.ll?rev=371776&r1=371775&r2=371776&view=diff
==============================================================================
--- llvm/trunk/test/Analysis/ScalarEvolution/max-expr-cache.ll (original)
+++ llvm/trunk/test/Analysis/ScalarEvolution/max-expr-cache.ll Thu Sep 12 14:32:27 2019
@@ -55,7 +55,7 @@ bb4:
   %tmp45 = icmp slt i32 %tmp43, 256
   %tmp46 = select i1 %tmp45, i32 %tmp43, i32 256
 ; CHECK:  %tmp46 = select i1 %tmp45, i32 %tmp43, i32 256
-; CHECK-NEXT:  -->  (256 smin (1 + (256 smin (1 + (256 smin (1 + (256 smin (1 + (256 smin (1 + (256 smin (1 + (256 smin (1 + (256 smin {%tmp3,+,-256}<%bb4>)) smin {%tmp3,+,-256}<%bb4>)) smin {%tmp3,+,-256}<%bb4>)) smin {%tmp3,+,-256}<%bb4>)) smin {%tmp3,+,-256}<%bb4>)) smin {%tmp3,+,-256}<%bb4>)) smin {%tmp3,+,-256}<%bb4>)) smin {%tmp3,+,-256}<%bb4>)
+; CHECK-NEXT:  -->  (256 smin (1 + (256 smin (1 + (256 smin (1 + (256 smin (1 + (256 smin (1 + (256 smin (1 + (256 smin (1 + (256 smin {%tmp3,+,-256}<%bb4>))<nsw> smin {%tmp3,+,-256}<%bb4>))<nsw> smin {%tmp3,+,-256}<%bb4>))<nsw> smin {%tmp3,+,-256}<%bb4>))<nsw> smin {%tmp3,+,-256}<%bb4>))<nsw> smin {%tmp3,+,-256}<%bb4>))<nsw> smin {%tmp3,+,-256}<%bb4>))<nsw> smin {%tmp3,+,-256}<%bb4>) U: [-2147483648,257) S: [-2147483648,257)
   %tmp47 = icmp sgt i32 %tmp44, %tmp46
   %tmp48 = select i1 %tmp47, i32 %tmp44, i32 %tmp46
   %tmp49 = ashr i32 %tmp48, 3
@@ -130,7 +130,7 @@ bb4:
   %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>))<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 }
+; 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)
   %tmp47 = icmp ugt i32 %tmp44, %tmp46
   %tmp48 = select i1 %tmp47, i32 %tmp44, i32 %tmp46
   %tmp49 = ashr i32 %tmp48, 3

Modified: llvm/trunk/test/Analysis/ScalarEvolution/trip-count15.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/ScalarEvolution/trip-count15.ll?rev=371776&r1=371775&r2=371776&view=diff
==============================================================================
--- llvm/trunk/test/Analysis/ScalarEvolution/trip-count15.ll (original)
+++ llvm/trunk/test/Analysis/ScalarEvolution/trip-count15.ll Thu Sep 12 14:32:27 2019
@@ -14,6 +14,8 @@ define void @umin_unsigned_check(i64 %n)
 ; 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>
+; CHECK-NEXT:   Predicates:
+; CHECK:       Loop %loop: Trip multiple is 1
 ;
 entry:
   %min.cmp = icmp ult i64 4096, %n
@@ -42,6 +44,8 @@ define void @umin_signed_check(i64 %n) {
 ; 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>
+; CHECK-NEXT:   Predicates:
+; CHECK:       Loop %loop: Trip multiple is 1
 ;
 entry:
   %min.cmp = icmp ult i64 4096, %n
@@ -61,15 +65,17 @@ define void @smin_signed_check(i64 %n) {
 ; CHECK-LABEL: 'smin_signed_check'
 ; CHECK-NEXT:  Classifying expressions for: @smin_signed_check
 ; CHECK-NEXT:    %min.n = select i1 %min.cmp, i64 4096, i64 %n
-; CHECK-NEXT:    --> (4096 smin %n) U: full-set S: full-set
+; CHECK-NEXT:    --> (4096 smin %n) U: [-9223372036854775808,4097) S: [-9223372036854775808,4097)
 ; 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: (0 smax (1 + (4096 smin %n))<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: (1 + (0 smax (1 + (4096 smin %n))<nsw>))<nuw><nsw> LoopDispositions: { %loop: Computable }
 ; CHECK-NEXT:  Determining loop execution counts for: @smin_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 (0 smax (1 + (4096 smin %n))<nsw>)
+; CHECK-NEXT:  Loop %loop: max backedge-taken count is 4097
+; CHECK-NEXT:  Loop %loop: Predicated backedge-taken count is (0 smax (1 + (4096 smin %n))<nsw>)
+; CHECK-NEXT:   Predicates:
+; CHECK:       Loop %loop: Trip multiple is 1
 ;
 entry:
   %min.cmp = icmp slt i64 4096, %n
@@ -89,7 +95,7 @@ define void @smin_unsigned_check(i64 %n)
 ; CHECK-LABEL: 'smin_unsigned_check'
 ; CHECK-NEXT:  Classifying expressions for: @smin_unsigned_check
 ; CHECK-NEXT:    %min.n = select i1 %min.cmp, i64 4096, i64 %n
-; CHECK-NEXT:    --> (4096 smin %n) U: full-set S: full-set
+; CHECK-NEXT:    --> (4096 smin %n) U: [-9223372036854775808,4097) S: [-9223372036854775808,4097)
 ; 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:    %iv.next = add i64 %iv, 1

Modified: llvm/trunk/test/Transforms/IRCE/rc-negative-bound.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/IRCE/rc-negative-bound.ll?rev=371776&r1=371775&r2=371776&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/IRCE/rc-negative-bound.ll (original)
+++ llvm/trunk/test/Transforms/IRCE/rc-negative-bound.ll Thu Sep 12 14:32:27 2019
@@ -114,18 +114,18 @@ define void @test_03(i32 *%arr, i32 %n,
 ; CHECK:       loop.preheader:
 ; CHECK-NEXT:    [[TMP0:%.*]] = add i32 [[BOUND:%.*]], -2147483647
 ; CHECK-NEXT:    [[TMP1:%.*]] = icmp sgt i32 [[TMP0]], 0
-; CHECK-NEXT:    [[SMIN:%.*]] = select i1 [[TMP1]], i32 [[TMP0]], i32 0
-; CHECK-NEXT:    [[TMP2:%.*]] = sub i32 [[BOUND]], [[SMIN]]
+; CHECK-NEXT:    [[SMAX:%.*]] = select i1 [[TMP1]], i32 [[TMP0]], i32 0
+; CHECK-NEXT:    [[TMP2:%.*]] = sub i32 [[BOUND]], [[SMAX]]
 ; CHECK-NEXT:    [[TMP3:%.*]] = icmp slt i32 [[BOUND]], 0
-; CHECK-NEXT:    [[SMAX:%.*]] = select i1 [[TMP3]], i32 [[BOUND]], i32 0
-; CHECK-NEXT:    [[TMP4:%.*]] = icmp sgt i32 [[SMAX]], -1
-; CHECK-NEXT:    [[SMIN1:%.*]] = select i1 [[TMP4]], i32 [[SMAX]], i32 -1
-; CHECK-NEXT:    [[TMP5:%.*]] = add i32 [[SMIN1]], 1
+; CHECK-NEXT:    [[SMIN:%.*]] = select i1 [[TMP3]], i32 [[BOUND]], i32 0
+; CHECK-NEXT:    [[TMP4:%.*]] = icmp sgt i32 [[SMIN]], -1
+; CHECK-NEXT:    [[SMAX1:%.*]] = select i1 [[TMP4]], i32 [[SMIN]], i32 -1
+; CHECK-NEXT:    [[TMP5:%.*]] = add nsw i32 [[SMAX1]], 1
 ; CHECK-NEXT:    [[TMP6:%.*]] = mul i32 [[TMP2]], [[TMP5]]
 ; CHECK-NEXT:    [[TMP7:%.*]] = icmp slt i32 [[N]], [[TMP6]]
-; CHECK-NEXT:    [[SMAX2:%.*]] = select i1 [[TMP7]], i32 [[N]], i32 [[TMP6]]
-; CHECK-NEXT:    [[TMP8:%.*]] = icmp sgt i32 [[SMAX2]], 0
-; CHECK-NEXT:    [[EXIT_MAINLOOP_AT:%.*]] = select i1 [[TMP8]], i32 [[SMAX2]], i32 0
+; CHECK-NEXT:    [[SMIN2:%.*]] = select i1 [[TMP7]], i32 [[N]], i32 [[TMP6]]
+; CHECK-NEXT:    [[TMP8:%.*]] = icmp sgt i32 [[SMIN2]], 0
+; CHECK-NEXT:    [[EXIT_MAINLOOP_AT:%.*]] = select i1 [[TMP8]], i32 [[SMIN2]], i32 0
 ; CHECK-NEXT:    [[TMP9:%.*]] = icmp slt i32 0, [[EXIT_MAINLOOP_AT]]
 ; CHECK-NEXT:    br i1 [[TMP9]], label [[LOOP_PREHEADER4:%.*]], label [[MAIN_PSEUDO_EXIT:%.*]]
 ; CHECK:       loop.preheader4:
@@ -207,11 +207,11 @@ define void @test_04(i32 *%arr, i32 %n,
 ; CHECK-NEXT:    br i1 [[FIRST_ITR_CHECK]], label [[LOOP_PREHEADER:%.*]], label [[EXIT:%.*]]
 ; CHECK:       loop.preheader:
 ; CHECK-NEXT:    [[TMP0:%.*]] = icmp slt i32 [[BOUND:%.*]], 0
-; CHECK-NEXT:    [[SMAX:%.*]] = select i1 [[TMP0]], i32 [[BOUND]], i32 0
-; CHECK-NEXT:    [[TMP1:%.*]] = sub i32 [[BOUND]], [[SMAX]]
-; CHECK-NEXT:    [[TMP2:%.*]] = icmp sgt i32 [[SMAX]], -1
-; CHECK-NEXT:    [[SMIN:%.*]] = select i1 [[TMP2]], i32 [[SMAX]], i32 -1
-; CHECK-NEXT:    [[TMP3:%.*]] = add i32 [[SMIN]], 1
+; CHECK-NEXT:    [[SMIN:%.*]] = select i1 [[TMP0]], i32 [[BOUND]], i32 0
+; CHECK-NEXT:    [[TMP1:%.*]] = sub i32 [[BOUND]], [[SMIN]]
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp sgt i32 [[SMIN]], -1
+; CHECK-NEXT:    [[SMAX:%.*]] = select i1 [[TMP2]], i32 [[SMIN]], i32 -1
+; CHECK-NEXT:    [[TMP3:%.*]] = add nsw i32 [[SMAX]], 1
 ; CHECK-NEXT:    [[TMP4:%.*]] = mul i32 [[TMP1]], [[TMP3]]
 ; CHECK-NEXT:    [[TMP5:%.*]] = icmp ult i32 [[N]], [[TMP4]]
 ; CHECK-NEXT:    [[EXIT_MAINLOOP_AT:%.*]] = select i1 [[TMP5]], i32 [[N]], i32 [[TMP4]]
@@ -402,18 +402,18 @@ define void @test_07(i32 *%arr, i32 %n,
 ; CHECK:       loop.preheader:
 ; CHECK-NEXT:    [[TMP0:%.*]] = add i32 [[BOUND:%.*]], -2147483647
 ; CHECK-NEXT:    [[TMP1:%.*]] = icmp sgt i32 [[TMP0]], 0
-; CHECK-NEXT:    [[SMIN:%.*]] = select i1 [[TMP1]], i32 [[TMP0]], i32 0
-; CHECK-NEXT:    [[TMP2:%.*]] = sub i32 [[BOUND]], [[SMIN]]
+; CHECK-NEXT:    [[SMAX:%.*]] = select i1 [[TMP1]], i32 [[TMP0]], i32 0
+; CHECK-NEXT:    [[TMP2:%.*]] = sub i32 [[BOUND]], [[SMAX]]
 ; CHECK-NEXT:    [[TMP3:%.*]] = icmp slt i32 [[BOUND]], 0
-; CHECK-NEXT:    [[SMAX:%.*]] = select i1 [[TMP3]], i32 [[BOUND]], i32 0
-; CHECK-NEXT:    [[TMP4:%.*]] = icmp sgt i32 [[SMAX]], -1
-; CHECK-NEXT:    [[SMIN1:%.*]] = select i1 [[TMP4]], i32 [[SMAX]], i32 -1
-; CHECK-NEXT:    [[TMP5:%.*]] = add i32 [[SMIN1]], 1
+; CHECK-NEXT:    [[SMIN:%.*]] = select i1 [[TMP3]], i32 [[BOUND]], i32 0
+; CHECK-NEXT:    [[TMP4:%.*]] = icmp sgt i32 [[SMIN]], -1
+; CHECK-NEXT:    [[SMAX1:%.*]] = select i1 [[TMP4]], i32 [[SMIN]], i32 -1
+; CHECK-NEXT:    [[TMP5:%.*]] = add nsw i32 [[SMAX1]], 1
 ; CHECK-NEXT:    [[TMP6:%.*]] = mul i32 [[TMP2]], [[TMP5]]
 ; CHECK-NEXT:    [[TMP7:%.*]] = icmp slt i32 [[N]], [[TMP6]]
-; CHECK-NEXT:    [[SMAX2:%.*]] = select i1 [[TMP7]], i32 [[N]], i32 [[TMP6]]
-; CHECK-NEXT:    [[TMP8:%.*]] = icmp sgt i32 [[SMAX2]], 0
-; CHECK-NEXT:    [[EXIT_MAINLOOP_AT:%.*]] = select i1 [[TMP8]], i32 [[SMAX2]], i32 0
+; CHECK-NEXT:    [[SMIN2:%.*]] = select i1 [[TMP7]], i32 [[N]], i32 [[TMP6]]
+; CHECK-NEXT:    [[TMP8:%.*]] = icmp sgt i32 [[SMIN2]], 0
+; CHECK-NEXT:    [[EXIT_MAINLOOP_AT:%.*]] = select i1 [[TMP8]], i32 [[SMIN2]], i32 0
 ; CHECK-NEXT:    [[TMP9:%.*]] = icmp slt i32 0, [[EXIT_MAINLOOP_AT]]
 ; CHECK-NEXT:    br i1 [[TMP9]], label [[LOOP_PREHEADER4:%.*]], label [[MAIN_PSEUDO_EXIT:%.*]]
 ; CHECK:       loop.preheader4:
@@ -497,11 +497,11 @@ define void @test_08(i32 *%arr, i32 %n,
 ; CHECK-NEXT:    br i1 [[FIRST_ITR_CHECK]], label [[LOOP_PREHEADER:%.*]], label [[EXIT:%.*]]
 ; CHECK:       loop.preheader:
 ; CHECK-NEXT:    [[TMP0:%.*]] = icmp slt i32 [[BOUND:%.*]], 0
-; CHECK-NEXT:    [[SMAX:%.*]] = select i1 [[TMP0]], i32 [[BOUND]], i32 0
-; CHECK-NEXT:    [[TMP1:%.*]] = sub i32 [[BOUND]], [[SMAX]]
-; CHECK-NEXT:    [[TMP2:%.*]] = icmp sgt i32 [[SMAX]], -1
-; CHECK-NEXT:    [[SMIN:%.*]] = select i1 [[TMP2]], i32 [[SMAX]], i32 -1
-; CHECK-NEXT:    [[TMP3:%.*]] = add i32 [[SMIN]], 1
+; CHECK-NEXT:    [[SMIN:%.*]] = select i1 [[TMP0]], i32 [[BOUND]], i32 0
+; CHECK-NEXT:    [[TMP1:%.*]] = sub i32 [[BOUND]], [[SMIN]]
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp sgt i32 [[SMIN]], -1
+; CHECK-NEXT:    [[SMAX:%.*]] = select i1 [[TMP2]], i32 [[SMIN]], i32 -1
+; CHECK-NEXT:    [[TMP3:%.*]] = add nsw i32 [[SMAX]], 1
 ; CHECK-NEXT:    [[TMP4:%.*]] = mul i32 [[TMP1]], [[TMP3]]
 ; CHECK-NEXT:    [[TMP5:%.*]] = icmp ult i32 [[N]], [[TMP4]]
 ; CHECK-NEXT:    [[EXIT_MAINLOOP_AT:%.*]] = select i1 [[TMP5]], i32 [[N]], i32 [[TMP4]]

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