[llvm] 5e16650 - [SCEV] `getSequentialMinMaxExpr()`: keep only the first instance of an operand
Roman Lebedev via llvm-commits
llvm-commits at lists.llvm.org
Tue Jan 11 05:52:09 PST 2022
Author: Roman Lebedev
Date: 2022-01-11T16:51:53+03:00
New Revision: 5e166507920165dfb08bf3a57aec80776929fcad
URL: https://github.com/llvm/llvm-project/commit/5e166507920165dfb08bf3a57aec80776929fcad
DIFF: https://github.com/llvm/llvm-project/commit/5e166507920165dfb08bf3a57aec80776929fcad.diff
LOG: [SCEV] `getSequentialMinMaxExpr()`: keep only the first instance of an operand
Having the same operand more than once doesn't change the outcome here,
neither reduction-wise nor poison-wise.
We must keep the first instance specifically though.
Added:
Modified:
llvm/lib/Analysis/ScalarEvolution.cpp
llvm/test/Analysis/ScalarEvolution/exit-count-select-safe.ll
Removed:
################################################################################
diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 160012b3d79a..02972c75ca48 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -3893,6 +3893,24 @@ ScalarEvolution::getSequentialMinMaxExpr(SCEVTypes Kind,
// FIXME: there are *some* simplifications that we can do here.
+ // Keep only the first instance of an operand.
+ {
+ SmallPtrSet<const SCEV *, 16> SeenOps;
+ unsigned Idx = 0;
+ bool DeletedAny = false;
+ while (Idx < Ops.size()) {
+ if (SeenOps.insert(Ops[Idx]).second) {
+ ++Idx;
+ continue;
+ }
+ Ops.erase(Ops.begin() + Idx);
+ DeletedAny = true;
+ }
+
+ if (DeletedAny)
+ return getSequentialMinMaxExpr(Kind, Ops);
+ }
+
// Check to see if one of the operands is of the same kind. If so, expand its
// operands onto our operand list, and recurse to simplify.
{
diff --git a/llvm/test/Analysis/ScalarEvolution/exit-count-select-safe.ll b/llvm/test/Analysis/ScalarEvolution/exit-count-select-safe.ll
index c0a1f99a417c..1050f259d363 100644
--- a/llvm/test/Analysis/ScalarEvolution/exit-count-select-safe.ll
+++ b/llvm/test/Analysis/ScalarEvolution/exit-count-select-safe.ll
@@ -129,9 +129,9 @@ define i32 @logical_or_3ops_duplicate(i32 %n, i32 %m, i32 %k) {
; CHECK-LABEL: 'logical_or_3ops_duplicate'
; CHECK-NEXT: Classifying expressions for: @logical_or_3ops_duplicate
; CHECK-NEXT: %i = phi i32 [ 0, %entry ], [ %i.next, %loop ]
-; CHECK-NEXT: --> {0,+,1}<%loop> U: full-set S: full-set Exits: (%n umin_seq %m umin_seq %n umin_seq %k) LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {0,+,1}<%loop> U: full-set S: full-set Exits: (%n umin_seq %m umin_seq %k) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %i.next = add i32 %i, 1
-; CHECK-NEXT: --> {1,+,1}<%loop> U: full-set S: full-set Exits: (1 + (%n umin_seq %m umin_seq %n umin_seq %k)) LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {1,+,1}<%loop> U: full-set S: full-set Exits: (1 + (%n umin_seq %m umin_seq %k)) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %cond_p4 = select i1 %cond_p0, i1 true, i1 %cond_p1
; CHECK-NEXT: --> %cond_p4 U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Variant }
; CHECK-NEXT: %cond_p5 = select i1 %cond_p4, i1 true, i1 %cond_p2
@@ -139,9 +139,9 @@ define i32 @logical_or_3ops_duplicate(i32 %n, i32 %m, i32 %k) {
; CHECK-NEXT: %cond = select i1 %cond_p5, i1 true, i1 %cond_p3
; CHECK-NEXT: --> %cond U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Variant }
; CHECK-NEXT: Determining loop execution counts for: @logical_or_3ops_duplicate
-; CHECK-NEXT: Loop %loop: backedge-taken count is (%n umin_seq %m umin_seq %n umin_seq %k)
+; CHECK-NEXT: Loop %loop: backedge-taken count is (%n umin_seq %m umin_seq %k)
; CHECK-NEXT: Loop %loop: max backedge-taken count is -1
-; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is (%n umin_seq %m umin_seq %n umin_seq %k)
+; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is (%n umin_seq %m umin_seq %k)
; CHECK-NEXT: Predicates:
; CHECK: Loop %loop: Trip multiple is 1
;
@@ -166,28 +166,28 @@ define i32 @computeSCEVAtScope(i32 %d.0) {
; CHECK-LABEL: 'computeSCEVAtScope'
; CHECK-NEXT: Classifying expressions for: @computeSCEVAtScope
; CHECK-NEXT: %d.1 = phi i32 [ %inc, %for.body ], [ %d.0, %for.cond.preheader ]
-; CHECK-NEXT: --> {%d.0,+,1}<nsw><%for.cond> U: full-set S: full-set Exits: (((-1 * %d.0) umin_seq (-1 * %d.0)) + %d.0) LoopDispositions: { %for.cond: Computable, %while.cond: Variant }
+; CHECK-NEXT: --> {%d.0,+,1}<nsw><%for.cond> U: full-set S: full-set Exits: 0 LoopDispositions: { %for.cond: Computable, %while.cond: Variant }
; CHECK-NEXT: %e.1 = phi i32 [ %inc3, %for.body ], [ %d.0, %for.cond.preheader ]
-; CHECK-NEXT: --> {%d.0,+,1}<nsw><%for.cond> U: full-set S: full-set Exits: (((-1 * %d.0) umin_seq (-1 * %d.0)) + %d.0) LoopDispositions: { %for.cond: Computable, %while.cond: Variant }
+; CHECK-NEXT: --> {%d.0,+,1}<nsw><%for.cond> U: full-set S: full-set Exits: 0 LoopDispositions: { %for.cond: Computable, %while.cond: Variant }
; CHECK-NEXT: %0 = select i1 %tobool1, i1 %tobool2, i1 false
-; CHECK-NEXT: --> %0 U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %for.cond: Variant, %while.cond: Variant }
+; CHECK-NEXT: --> %0 U: full-set S: full-set Exits: false LoopDispositions: { %for.cond: Variant, %while.cond: Variant }
; CHECK-NEXT: %inc = add nsw i32 %d.1, 1
-; CHECK-NEXT: --> {(1 + %d.0),+,1}<nw><%for.cond> U: full-set S: full-set Exits: (1 + ((-1 * %d.0) umin_seq (-1 * %d.0)) + %d.0) LoopDispositions: { %for.cond: Computable, %while.cond: Variant }
+; CHECK-NEXT: --> {(1 + %d.0),+,1}<nw><%for.cond> U: full-set S: full-set Exits: 1 LoopDispositions: { %for.cond: Computable, %while.cond: Variant }
; CHECK-NEXT: %inc3 = add nsw i32 %e.1, 1
-; CHECK-NEXT: --> {(1 + %d.0),+,1}<nw><%for.cond> U: full-set S: full-set Exits: (1 + ((-1 * %d.0) umin_seq (-1 * %d.0)) + %d.0) LoopDispositions: { %for.cond: Computable, %while.cond: Variant }
+; CHECK-NEXT: --> {(1 + %d.0),+,1}<nw><%for.cond> U: full-set S: full-set Exits: 1 LoopDispositions: { %for.cond: Computable, %while.cond: Variant }
; CHECK-NEXT: %f.1 = phi i32 [ %inc8, %for.body5 ], [ 0, %for.cond4.preheader ]
-; CHECK-NEXT: --> {0,+,1}<%for.cond4> U: full-set S: full-set Exits: (((-1 * %d.0) umin_seq (-1 * %d.0)) + %d.0) LoopDispositions: { %for.cond4: Computable, %while.cond: Variant }
+; CHECK-NEXT: --> {0,+,1}<%for.cond4> U: [0,1) S: [0,1) Exits: 0 LoopDispositions: { %for.cond4: Computable, %while.cond: Variant }
; CHECK-NEXT: %inc8 = add i32 %f.1, 1
-; CHECK-NEXT: --> {1,+,1}<%for.cond4> U: full-set S: full-set Exits: (1 + ((-1 * %d.0) umin_seq (-1 * %d.0)) + %d.0) LoopDispositions: { %for.cond4: Computable, %while.cond: Variant }
+; CHECK-NEXT: --> {1,+,1}<%for.cond4> U: [1,2) S: [1,2) Exits: 1 LoopDispositions: { %for.cond4: Computable, %while.cond: Variant }
; CHECK-NEXT: Determining loop execution counts for: @computeSCEVAtScope
-; CHECK-NEXT: Loop %for.cond: backedge-taken count is ((-1 * %d.0) umin_seq (-1 * %d.0))
+; CHECK-NEXT: Loop %for.cond: backedge-taken count is (-1 * %d.0)
; CHECK-NEXT: Loop %for.cond: max backedge-taken count is -1
-; CHECK-NEXT: Loop %for.cond: Predicated backedge-taken count is ((-1 * %d.0) umin_seq (-1 * %d.0))
+; CHECK-NEXT: Loop %for.cond: Predicated backedge-taken count is (-1 * %d.0)
; CHECK-NEXT: Predicates:
; CHECK: Loop %for.cond: Trip multiple is 1
-; CHECK-NEXT: Loop %for.cond4: backedge-taken count is (((-1 * %d.0) umin_seq (-1 * %d.0)) + %d.0)
-; CHECK-NEXT: Loop %for.cond4: max backedge-taken count is -1
-; CHECK-NEXT: Loop %for.cond4: Predicated backedge-taken count is (((-1 * %d.0) umin_seq (-1 * %d.0)) + %d.0)
+; CHECK-NEXT: Loop %for.cond4: backedge-taken count is 0
+; CHECK-NEXT: Loop %for.cond4: max backedge-taken count is 0
+; CHECK-NEXT: Loop %for.cond4: Predicated backedge-taken count is 0
; CHECK-NEXT: Predicates:
; CHECK: Loop %for.cond4: Trip multiple is 1
; CHECK-NEXT: Loop %while.cond: <multiple exits> Unpredictable backedge-taken count.
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