Index: lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp =================================================================== --- lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp +++ lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp @@ -79,6 +79,9 @@ static cl::opt SkipProfitabilityChecks("irce-skip-profitability-checks", cl::Hidden, cl::init(false)); +static cl::opt AllowUnsignedLatchCondition("irce-allow-unsigned-latch", + cl::Hidden, cl::init(false)); + static const char *ClonedLoopTag = "irce.loop.clone"; #define DEBUG_TYPE "irce" @@ -889,6 +892,15 @@ IsSignedPredicate = Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SGT; + + // FIXME: We temporarily disable unsigned latch conditions by default + // because of found problems with intersecting signed and unsigned ranges. + // We are going to turn it on once the problems are fixed. + if (!IsSignedPredicate && !AllowUnsignedLatchCondition) { + FailureReason = "unsigned latch conditions are explicitly prohibited"; + return None; + } + // The predicate that we need to check that the induction variable lies // within bounds. ICmpInst::Predicate BoundPred = @@ -964,6 +976,15 @@ IsSignedPredicate = Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SGT; + + // FIXME: We temporarily disable unsigned latch conditions by default + // because of found problems with intersecting signed and unsigned ranges. + // We are going to turn it on once the problems are fixed. + if (!IsSignedPredicate && !AllowUnsignedLatchCondition) { + FailureReason = "unsigned latch conditions are explicitly prohibited"; + return None; + } + // The predicate that we need to check that the induction variable lies // within bounds. ICmpInst::Predicate BoundPred = Index: test/Transforms/IRCE/clamp.ll =================================================================== --- test/Transforms/IRCE/clamp.ll +++ test/Transforms/IRCE/clamp.ll @@ -1,4 +1,4 @@ -; RUN: opt -verify-loop-info -irce-print-changed-loops -irce -S < %s 2>&1 | FileCheck %s +; RUN: opt -verify-loop-info -irce-print-changed-loops -irce -irce-allow-unsigned-latch=true -S < %s 2>&1 | FileCheck %s ; The test demonstrates that incorrect behavior of Clamp may lead to incorrect ; calculation of post-loop exit condition. Index: test/Transforms/IRCE/eq_ne.ll =================================================================== --- test/Transforms/IRCE/eq_ne.ll +++ test/Transforms/IRCE/eq_ne.ll @@ -1,4 +1,4 @@ -; RUN: opt -verify-loop-info -irce-print-changed-loops -irce -S < %s 2>&1 | FileCheck %s +; RUN: opt -verify-loop-info -irce-print-changed-loops -irce -irce-allow-unsigned-latch=true -S < %s 2>&1 | FileCheck %s ; CHECK: irce: in function test_01: constrained Loop at depth 1 containing: %loop
,%in.bounds ; CHECK: irce: in function test_01u: constrained Loop at depth 1 containing: %loop
,%in.bounds Index: test/Transforms/IRCE/range_intersect_miscompile.ll =================================================================== --- test/Transforms/IRCE/range_intersect_miscompile.ll +++ test/Transforms/IRCE/range_intersect_miscompile.ll @@ -0,0 +1,45 @@ +; RUN: opt -irce -S < %s 2>&1 | FileCheck %s + +; This test demonstrates a miscompile: the outer loop's IV iterates in range of +; [2, 400) and the range check is done against value 331. Due to a bug in range +; intersection IRCE manages to eliminate the range check without inserting a +; postloop, which is incorrect. So far IRCE is prohibited for this case. + +define void @test_01() { + +; CHECK-LABEL: test_01 +; CHECK-NOT: br i1 true + +entry: + br label %loop_header + +loop_header: ; preds = %loop_latch, %entry + %iv = phi i32 [ 2, %entry ], [ %iv_next, %loop_latch ] + %iv.prev = phi i32 [ 1, %entry ], [ %iv, %loop_latch ] + %tmp2 = icmp sgt i32 %iv.prev, -1 + br i1 %tmp2, label %loop_header.split.us, label %exit + +loop_header.split.us: ; preds = %loop_header + br label %inner_loop + +inner_loop: ; preds = %inner_loop, %loop_header.split.us + %inner_iv = phi i32 [ 1, %loop_header.split.us ], [ %inner_iv_next, %inner_loop ] + %inner_iv_next = add nuw nsw i32 %inner_iv, 1 + %inner_cond = icmp ult i32 %inner_iv_next, 31 + br i1 %inner_cond, label %inner_loop, label %range_check_block + +exit: ; preds = %loop_latch, %loop_header + ret void + +range_check_block: ; preds = %inner_loop + %range_check = icmp slt i32 %iv, 331 + br i1 %range_check, label %loop_latch, label %deopt + +loop_latch: ; preds = %range_check_block + %iv_next = add i32 %iv, 1 + %loop_cond = icmp ult i32 %iv_next, 400 + br i1 %loop_cond, label %loop_header, label %exit + +deopt: ; preds = %range_check_block + ret void +} Index: test/Transforms/IRCE/stride_more_than_1.ll =================================================================== --- test/Transforms/IRCE/stride_more_than_1.ll +++ test/Transforms/IRCE/stride_more_than_1.ll @@ -1,4 +1,4 @@ -; RUN: opt -verify-loop-info -irce-print-changed-loops -irce -S < %s 2>&1 | FileCheck %s +; RUN: opt -verify-loop-info -irce-print-changed-loops -irce -irce-allow-unsigned-latch=true -S < %s 2>&1 | FileCheck %s ; CHECK: irce: in function test_01: constrained Loop at depth 1 containing: %loop
,%in.bounds ; CHECK: irce: in function test_02: constrained Loop at depth 1 containing: %loop
,%in.bounds Index: test/Transforms/IRCE/unsigned_comparisons_ugt.ll =================================================================== --- test/Transforms/IRCE/unsigned_comparisons_ugt.ll +++ test/Transforms/IRCE/unsigned_comparisons_ugt.ll @@ -1,4 +1,4 @@ -; RUN: opt -verify-loop-info -irce-print-changed-loops -irce -S < %s 2>&1 | FileCheck %s +; RUN: opt -verify-loop-info -irce-print-changed-loops -irce -irce-allow-unsigned-latch=true -S < %s 2>&1 | FileCheck %s ; CHECK: irce: in function test_01: constrained Loop at depth 1 containing: %loop
,%in.bounds ; CHECK: irce: in function test_02: constrained Loop at depth 1 containing: %loop
,%in.bounds Index: test/Transforms/IRCE/unsigned_comparisons_ult.ll =================================================================== --- test/Transforms/IRCE/unsigned_comparisons_ult.ll +++ test/Transforms/IRCE/unsigned_comparisons_ult.ll @@ -1,4 +1,4 @@ -; RUN: opt -verify-loop-info -irce-print-changed-loops -irce -S < %s 2>&1 | FileCheck %s +; RUN: opt -verify-loop-info -irce-print-changed-loops -irce -irce-allow-unsigned-latch=true -S < %s 2>&1 | FileCheck %s ; CHECK: irce: in function test_01: constrained Loop at depth 1 containing: %loop
,%in.bounds ; CHECK: irce: in function test_02: constrained Loop at depth 1 containing: %loop
,%in.bounds