From 41c729e78ec61f47c9b44978a58b23120347d18f Mon Sep 17 00:00:00 2001 From: Mircea Trofin Date: Thu, 13 Dec 2018 19:40:59 +0000 Subject: [llvm] Address base discriminator overflow in X86DiscriminateMemOps Summary: Macros are expanded on a single line. In case of large expansions, with sufficiently many instructions with memory operands (and when -fdebug-info-for-profiling is requested), we may be unable to generate new base discriminator values - new values overflow (base discriminators may not be larger than 2^12). This CL warns instead of asserting in such a case. A subsequent CL will add APIs to check for overflow before creating new debug info. See https://bugs.llvm.org/show_bug.cgi?id=39890 Reviewers: davidxl, wmi, gbedwell Reviewed By: davidxl Subscribers: aprantl, llvm-commits Differential Revision: https://reviews.llvm.org/D55643 llvm-svn: 349075 --- llvm/lib/Target/X86/X86DiscriminateMemOps.cpp | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) (limited to 'llvm/lib/Target/X86/X86DiscriminateMemOps.cpp') diff --git a/llvm/lib/Target/X86/X86DiscriminateMemOps.cpp b/llvm/lib/Target/X86/X86DiscriminateMemOps.cpp index 4ab32ab53e5..5653babedf8 100644 --- a/llvm/lib/Target/X86/X86DiscriminateMemOps.cpp +++ b/llvm/lib/Target/X86/X86DiscriminateMemOps.cpp @@ -24,6 +24,8 @@ #include "llvm/Transforms/IPO/SampleProfile.h" using namespace llvm; +#define DEBUG_TYPE "x86-discriminate-memops" + namespace { using Location = std::pair; @@ -114,9 +116,18 @@ bool X86DiscriminateMemOps::runOnMachineFunction(MachineFunction &MF) { Changed = true; const std::pair::iterator, bool> MustInsert = Set.insert(DI->getBaseDiscriminator()); - (void)MustInsert; // silence warning. - assert(MustInsert.second && - "New discriminator shouldn't be present in set"); + // FIXME (mtrofin): check if the to-be inserted base discriminator can + // be added. This requires a new API on DILocation. + // The assumption is that this scenario is infrequent/OK not to support. + // If evidence points otherwise, we can explore synthesize unique DIs by + // adding fake line numbers. + if (!MustInsert.second) { + LLVM_DEBUG(dbgs() + << "Unable to create a unique discriminator in " + << DI->getFilename() << " Line: " << DI->getLine() + << " Column: " << DI->getColumn() + << ". This is likely due to a large macro expansion.\n"); + } } // Bump the reference DI to avoid cramming discriminators on line 0. -- cgit v1.2.3