[llvm] 0c4a735 - [SCEV] Support sext in SCEVLoopGuardRewriter
Max Kazantsev via llvm-commits
llvm-commits at lists.llvm.org
Mon Feb 6 23:00:41 PST 2023
Author: Max Kazantsev
Date: 2023-02-07T14:00:30+07:00
New Revision: 0c4a7352004da149319d2ec9717985c7ba621082
URL: https://github.com/llvm/llvm-project/commit/0c4a7352004da149319d2ec9717985c7ba621082
DIFF: https://github.com/llvm/llvm-project/commit/0c4a7352004da149319d2ec9717985c7ba621082.diff
LOG: [SCEV] Support sext in SCEVLoopGuardRewriter
There is no particular reason why it's not supported, and it is useful.
Differential Revision: https://reviews.llvm.org/D143257
Reviewed By: fhahn
Added:
Modified:
llvm/lib/Analysis/ScalarEvolution.cpp
llvm/test/Analysis/ScalarEvolution/max-backedge-taken-count-guard-info-rewrite-expressions.ll
Removed:
################################################################################
diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 723436598eb91..3bbb818654fd7 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -14933,9 +14933,6 @@ ScalarEvolution::computeSymbolicMaxBackedgeTakenCount(const Loop *L) {
/// A rewriter to replace SCEV expressions in Map with the corresponding entry
/// in the map. It skips AddRecExpr because we cannot guarantee that the
/// replacement is loop invariant in the loop of the AddRec.
-///
-/// At the moment only rewriting SCEVUnknown and SCEVZeroExtendExpr is
-/// supported.
class SCEVLoopGuardRewriter : public SCEVRewriteVisitor<SCEVLoopGuardRewriter> {
const DenseMap<const SCEV *, const SCEV *> ⤅
@@ -14960,6 +14957,14 @@ class SCEVLoopGuardRewriter : public SCEVRewriteVisitor<SCEVLoopGuardRewriter> {
Expr);
return I->second;
}
+
+ const SCEV *visitSignExtendExpr(const SCEVSignExtendExpr *Expr) {
+ auto I = Map.find(Expr);
+ if (I == Map.end())
+ return SCEVRewriteVisitor<SCEVLoopGuardRewriter>::visitSignExtendExpr(
+ Expr);
+ return I->second;
+ }
};
const SCEV *ScalarEvolution::applyLoopGuards(const SCEV *Expr, const Loop *L) {
diff --git a/llvm/test/Analysis/ScalarEvolution/max-backedge-taken-count-guard-info-rewrite-expressions.ll b/llvm/test/Analysis/ScalarEvolution/max-backedge-taken-count-guard-info-rewrite-expressions.ll
index a6d3cb06e1ba5..5d7548de7a7d8 100644
--- a/llvm/test/Analysis/ScalarEvolution/max-backedge-taken-count-guard-info-rewrite-expressions.ll
+++ b/llvm/test/Analysis/ScalarEvolution/max-backedge-taken-count-guard-info-rewrite-expressions.ll
@@ -185,7 +185,7 @@ exit:
ret i32 0
}
-; TODO: same as rewrite_zext_min_max, but everything is signed.
+; same as rewrite_zext_min_max, but everything is signed.
; It should be able to prove the same exit count.
define i32 @rewrite_sext_min_max(i32 %N, ptr %arr) {
; CHECK-LABEL: 'rewrite_sext_min_max'
@@ -197,14 +197,14 @@ define i32 @rewrite_sext_min_max(i32 %N, ptr %arr) {
; CHECK-NEXT: %n.vec = and i64 %ext, 28
; CHECK-NEXT: --> (4 * (zext i3 (trunc i64 ((sext i32 (16 smin %N) to i64) /u 4) to i3) to i64))<nuw><nsw> U: [0,29) S: [0,29)
; CHECK-NEXT: %index = phi i64 [ 0, %loop.ph ], [ %index.next, %loop ]
-; CHECK-NEXT: --> {0,+,4}<nuw><nsw><%loop> U: [0,-9223372036854775808) S: [0,9223372036854775805) Exits: (4 * ((-4 + (4 * (zext i3 (trunc i64 ((sext i32 (16 smin %N) to i64) /u 4) to i3) to i64))<nuw><nsw>)<nsw> /u 4))<nuw> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {0,+,4}<nuw><nsw><%loop> U: [0,13) S: [0,13) Exits: (4 * ((-4 + (4 * (zext i3 (trunc i64 ((sext i32 (16 smin %N) to i64) /u 4) to i3) to i64))<nuw><nsw>)<nsw> /u 4))<nuw> LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %gep = getelementptr inbounds i32, ptr %arr, i64 %index
; CHECK-NEXT: --> {%arr,+,16}<nuw><%loop> U: full-set S: full-set Exits: ((16 * ((-4 + (4 * (zext i3 (trunc i64 ((sext i32 (16 smin %N) to i64) /u 4) to i3) to i64))<nuw><nsw>)<nsw> /u 4)) + %arr) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %index.next = add nsw i64 %index, 4
-; CHECK-NEXT: --> {4,+,4}<nuw><nsw><%loop> U: [4,-9223372036854775808) S: [4,9223372036854775805) Exits: (4 + (4 * ((-4 + (4 * (zext i3 (trunc i64 ((sext i32 (16 smin %N) to i64) /u 4) to i3) to i64))<nuw><nsw>)<nsw> /u 4))<nuw>) LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {4,+,4}<nuw><nsw><%loop> U: [4,17) S: [4,17) Exits: (4 + (4 * ((-4 + (4 * (zext i3 (trunc i64 ((sext i32 (16 smin %N) to i64) /u 4) to i3) to i64))<nuw><nsw>)<nsw> /u 4))<nuw>) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: Determining loop execution counts for: @rewrite_sext_min_max
; CHECK-NEXT: Loop %loop: backedge-taken count is ((-4 + (4 * (zext i3 (trunc i64 ((sext i32 (16 smin %N) to i64) /u 4) to i3) to i64))<nuw><nsw>)<nsw> /u 4)
-; CHECK-NEXT: Loop %loop: constant max backedge-taken count is 4611686018427387903
+; CHECK-NEXT: Loop %loop: constant max backedge-taken count is 3
; CHECK-NEXT: Loop %loop: symbolic max backedge-taken count is ((-4 + (4 * (zext i3 (trunc i64 ((sext i32 (16 smin %N) to i64) /u 4) to i3) to i64))<nuw><nsw>)<nsw> /u 4)
; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is ((-4 + (4 * (zext i3 (trunc i64 ((sext i32 (16 smin %N) to i64) /u 4) to i3) to i64))<nuw><nsw>)<nsw> /u 4)
; CHECK-NEXT: Predicates:
More information about the llvm-commits
mailing list