From e45168c4fa7debe61ec0fdb6ddae347e18477d37 Mon Sep 17 00:00:00 2001 From: Nikita Popov Date: Fri, 23 Apr 2021 22:02:27 +0200 Subject: [PATCH] [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 --- llvm/lib/Analysis/ScalarEvolution.cpp | 9 +++++++ .../max-backedge-taken-count-guard-info.ll | 24 +++++++++---------- 2 files changed, 21 insertions(+), 12 deletions(-) diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp index 488f60de41e4..4de5abfdc3f1 100644 --- a/llvm/lib/Analysis/ScalarEvolution.cpp +++ b/llvm/lib/Analysis/ScalarEvolution.cpp @@ -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(RHS)) RewriteMap[LHSUnknown->getValue()] = RHS; diff --git a/llvm/test/Analysis/ScalarEvolution/max-backedge-taken-count-guard-info.ll b/llvm/test/Analysis/ScalarEvolution/max-backedge-taken-count-guard-info.ll index ab64b154c58b..e5df81dfb6a5 100644 --- a/llvm/test/Analysis/ScalarEvolution/max-backedge-taken-count-guard-info.ll +++ b/llvm/test/Analysis/ScalarEvolution/max-backedge-taken-count-guard-info.ll @@ -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)),+,-1}<%while.body> U: full-set S: full-set Exits: 0 LoopDispositions: { %while.body: Computable } +; CHECK-NEXT: --> {(-1 + (%blockSize /u 4)),+,-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)) -; 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)) ; 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)),+,-1}<%while.body> U: full-set S: full-set Exits: 0 LoopDispositions: { %while.body: Computable } +; CHECK-NEXT: --> {(-1 + (%blockSize /u 4)),+,-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)) -; 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)) ; 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)),+,-1}<%while.body> U: full-set S: full-set Exits: 0 LoopDispositions: { %while.body: Computable } +; CHECK-NEXT: --> {(-1 + (%blockSize /u 4)),+,-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)) -; 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)) ; 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)),+,-1}<%while.body> U: full-set S: full-set Exits: 0 LoopDispositions: { %while.body: Computable } +; CHECK-NEXT: --> {(-1 + (%blockSize /u 4)),+,-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)) -; 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)) ; CHECK-NEXT: Predicates: ; CHECK: Loop %while.body: Trip multiple is 1