From ce54b22657f01d1c40de4941ceb6e7119848aecf Mon Sep 17 00:00:00 2001 From: Bruno Cardoso Lopes Date: Tue, 24 May 2022 16:56:22 -0700 Subject: [Clang][CoverageMapping] Fix switch counter codegen compile time explosion C++ generated code with huge amount of switch cases chokes badly while emitting coverage mapping, in our specific testcase (~72k cases), it won't stop after hours. After this change, the frontend job now finishes in 4.5s and shrinks down `@__covrec_` by 288k when compared to disabling simplification altogether. There's probably no good way to create a testcase for this, but it's easy to reproduce, just add thousands of cases in the below switch, and build with `-fprofile-instr-generate -fcoverage-mapping`. ``` enum type : int { FEATURE_INVALID = 0, FEATURE_A = 1, ... }; const char *to_string(type e) { switch (e) { case type::FEATURE_INVALID: return "FEATURE_INVALID"; case type::FEATURE_A: return "FEATURE_A";} ... } ``` Differential Revision: https://reviews.llvm.org/D126345 --- llvm/lib/ProfileData/Coverage/CoverageMapping.cpp | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) (limited to 'llvm/lib/ProfileData/Coverage/CoverageMapping.cpp') diff --git a/llvm/lib/ProfileData/Coverage/CoverageMapping.cpp b/llvm/lib/ProfileData/Coverage/CoverageMapping.cpp index 94c2bee..f9e58fd 100644 --- a/llvm/lib/ProfileData/Coverage/CoverageMapping.cpp +++ b/llvm/lib/ProfileData/Coverage/CoverageMapping.cpp @@ -123,13 +123,15 @@ Counter CounterExpressionBuilder::simplify(Counter ExpressionTree) { return C; } -Counter CounterExpressionBuilder::add(Counter LHS, Counter RHS) { - return simplify(get(CounterExpression(CounterExpression::Add, LHS, RHS))); +Counter CounterExpressionBuilder::add(Counter LHS, Counter RHS, bool Simplify) { + auto Cnt = get(CounterExpression(CounterExpression::Add, LHS, RHS)); + return Simplify ? simplify(Cnt) : Cnt; } -Counter CounterExpressionBuilder::subtract(Counter LHS, Counter RHS) { - return simplify( - get(CounterExpression(CounterExpression::Subtract, LHS, RHS))); +Counter CounterExpressionBuilder::subtract(Counter LHS, Counter RHS, + bool Simplify) { + auto Cnt = get(CounterExpression(CounterExpression::Subtract, LHS, RHS)); + return Simplify ? simplify(Cnt) : Cnt; } void CounterMappingContext::dump(const Counter &C, raw_ostream &OS) const { -- cgit v1.1