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[SCEV] Handle uge/ugt predicates in applyLoopGuards() 

These can be handled the same way as ule/ult, just using umax
instead of umin. This is useful in cases where the umax prevents
the upper bound from overflowing.

Differential Revision: https://reviews.llvm.org/D101196
This commit is contained in:
Nikita Popov 2021-04-23 22:02:27 +02:00
parent 1c0ab3411a
commit e45168c4fa
2 changed files with 21 additions and 12 deletions
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9
llvm/lib/Analysis/ScalarEvolution.cpp
View File

@ -13449,6 +13449,15 @@ const SCEV *ScalarEvolution::applyLoopGuards(const SCEV *Expr, const Loop *L) {
if (!containsAddRecurrence(RHS))
RewriteMap[LHSUnknown->getValue()] = getUMinExpr(RewrittenLHS, RHS);
break;
case CmpInst::ICMP_UGT:
if (!containsAddRecurrence(RHS))
RewriteMap[LHSUnknown->getValue()] =
getUMaxExpr(RewrittenLHS, getAddExpr(RHS, getOne(RHS->getType())));
break;
case CmpInst::ICMP_UGE:
if (!containsAddRecurrence(RHS))
RewriteMap[LHSUnknown->getValue()] = getUMaxExpr(RewrittenLHS, RHS);
break;
case CmpInst::ICMP_EQ:
if (isa<SCEVConstant>(RHS))
RewriteMap[LHSUnknown->getValue()] = RHS;

24
llvm/test/Analysis/ScalarEvolution/max-backedge-taken-count-guard-info.ll
View File

@ -622,12 +622,12 @@ define void @test_guard_uge(i32 %blockSize) {
; CHECK-NEXT: %shr = lshr i32 %blockSize, 2
; CHECK-NEXT: --> (%blockSize /u 4) U: [0,1073741824) S: [0,1073741824)
; CHECK-NEXT: %iv = phi i32 [ %dec, %while.body ], [ %shr, %while.body.preheader ]
; CHECK-NEXT: --> {(%blockSize /u 4),+,-1}<%while.body> U: full-set S: full-set Exits: 1 LoopDispositions: { %while.body: Computable }
; CHECK-NEXT: --> {(%blockSize /u 4),+,-1}<%while.body> U: [-1073741822,1073741824) S: [-1073741822,1073741824) Exits: 1 LoopDispositions: { %while.body: Computable }
; CHECK-NEXT: %dec = add i32 %iv, -1
; CHECK-NEXT: --> {(-1 + (%blockSize /u 4))<nsw>,+,-1}<%while.body> U: full-set S: full-set Exits: 0 LoopDispositions: { %while.body: Computable }
; CHECK-NEXT: --> {(-1 + (%blockSize /u 4))<nsw>,+,-1}<%while.body> U: [-1073741823,1073741823) S: [-1073741823,1073741823) Exits: 0 LoopDispositions: { %while.body: Computable }
; CHECK-NEXT: Determining loop execution counts for: @test_guard_uge
; CHECK-NEXT: Loop %while.body: backedge-taken count is (-1 + (%blockSize /u 4))<nsw>
; CHECK-NEXT: Loop %while.body: max backedge-taken count is -1
; CHECK-NEXT: Loop %while.body: max backedge-taken count is 1073741822
; CHECK-NEXT: Loop %while.body: Predicated backedge-taken count is (-1 + (%blockSize /u 4))<nsw>
; CHECK-NEXT: Predicates:
; CHECK: Loop %while.body: Trip multiple is 1
@ -658,12 +658,12 @@ define void @test_guard_ugt(i32 %blockSize) {
; CHECK-NEXT: %shr = lshr i32 %blockSize, 2
; CHECK-NEXT: --> (%blockSize /u 4) U: [0,1073741824) S: [0,1073741824)
; CHECK-NEXT: %iv = phi i32 [ %dec, %while.body ], [ %shr, %while.body.preheader ]
; CHECK-NEXT: --> {(%blockSize /u 4),+,-1}<%while.body> U: full-set S: full-set Exits: 1 LoopDispositions: { %while.body: Computable }
; CHECK-NEXT: --> {(%blockSize /u 4),+,-1}<%while.body> U: [-1073741822,1073741824) S: [-1073741822,1073741824) Exits: 1 LoopDispositions: { %while.body: Computable }
; CHECK-NEXT: %dec = add i32 %iv, -1
; CHECK-NEXT: --> {(-1 + (%blockSize /u 4))<nsw>,+,-1}<%while.body> U: full-set S: full-set Exits: 0 LoopDispositions: { %while.body: Computable }
; CHECK-NEXT: --> {(-1 + (%blockSize /u 4))<nsw>,+,-1}<%while.body> U: [-1073741823,1073741823) S: [-1073741823,1073741823) Exits: 0 LoopDispositions: { %while.body: Computable }
; CHECK-NEXT: Determining loop execution counts for: @test_guard_ugt
; CHECK-NEXT: Loop %while.body: backedge-taken count is (-1 + (%blockSize /u 4))<nsw>
; CHECK-NEXT: Loop %while.body: max backedge-taken count is -1
; CHECK-NEXT: Loop %while.body: max backedge-taken count is 1073741822
; CHECK-NEXT: Loop %while.body: Predicated backedge-taken count is (-1 + (%blockSize /u 4))<nsw>
; CHECK-NEXT: Predicates:
; CHECK: Loop %while.body: Trip multiple is 1
@ -694,12 +694,12 @@ define void @test_guard_uge_and_ule(i32 %blockSize) {
; CHECK-NEXT: %shr = lshr i32 %blockSize, 2
; CHECK-NEXT: --> (%blockSize /u 4) U: [0,1073741824) S: [0,1073741824)
; CHECK-NEXT: %iv = phi i32 [ %dec, %while.body ], [ %shr, %while.body.preheader ]
; CHECK-NEXT: --> {(%blockSize /u 4),+,-1}<%while.body> U: full-set S: full-set Exits: 1 LoopDispositions: { %while.body: Computable }
; CHECK-NEXT: --> {(%blockSize /u 4),+,-1}<%while.body> U: [-255,1073741824) S: [-255,1073741824) Exits: 1 LoopDispositions: { %while.body: Computable }
; CHECK-NEXT: %dec = add i32 %iv, -1
; CHECK-NEXT: --> {(-1 + (%blockSize /u 4))<nsw>,+,-1}<%while.body> U: full-set S: full-set Exits: 0 LoopDispositions: { %while.body: Computable }
; CHECK-NEXT: --> {(-1 + (%blockSize /u 4))<nsw>,+,-1}<%while.body> U: [-256,1073741823) S: [-256,1073741823) Exits: 0 LoopDispositions: { %while.body: Computable }
; CHECK-NEXT: Determining loop execution counts for: @test_guard_uge_and_ule
; CHECK-NEXT: Loop %while.body: backedge-taken count is (-1 + (%blockSize /u 4))<nsw>
; CHECK-NEXT: Loop %while.body: max backedge-taken count is -1
; CHECK-NEXT: Loop %while.body: max backedge-taken count is 255
; CHECK-NEXT: Loop %while.body: Predicated backedge-taken count is (-1 + (%blockSize /u 4))<nsw>
; CHECK-NEXT: Predicates:
; CHECK: Loop %while.body: Trip multiple is 1
@ -734,12 +734,12 @@ define void @test_guard_ugt_and_ult(i32 %blockSize) {
; CHECK-NEXT: %shr = lshr i32 %blockSize, 2
; CHECK-NEXT: --> (%blockSize /u 4) U: [0,1073741824) S: [0,1073741824)
; CHECK-NEXT: %iv = phi i32 [ %dec, %while.body ], [ %shr, %while.body.preheader ]
; CHECK-NEXT: --> {(%blockSize /u 4),+,-1}<%while.body> U: full-set S: full-set Exits: 1 LoopDispositions: { %while.body: Computable }
; CHECK-NEXT: --> {(%blockSize /u 4),+,-1}<%while.body> U: [-255,1073741824) S: [-255,1073741824) Exits: 1 LoopDispositions: { %while.body: Computable }
; CHECK-NEXT: %dec = add i32 %iv, -1
; CHECK-NEXT: --> {(-1 + (%blockSize /u 4))<nsw>,+,-1}<%while.body> U: full-set S: full-set Exits: 0 LoopDispositions: { %while.body: Computable }
; CHECK-NEXT: --> {(-1 + (%blockSize /u 4))<nsw>,+,-1}<%while.body> U: [-256,1073741823) S: [-256,1073741823) Exits: 0 LoopDispositions: { %while.body: Computable }
; CHECK-NEXT: Determining loop execution counts for: @test_guard_ugt_and_ult
; CHECK-NEXT: Loop %while.body: backedge-taken count is (-1 + (%blockSize /u 4))<nsw>
; CHECK-NEXT: Loop %while.body: max backedge-taken count is -1
; CHECK-NEXT: Loop %while.body: max backedge-taken count is 255
; CHECK-NEXT: Loop %while.body: Predicated backedge-taken count is (-1 + (%blockSize /u 4))<nsw>
; CHECK-NEXT: Predicates:
; CHECK: Loop %while.body: Trip multiple is 1