From cb22ab7403557941fd672a8fc3a16b1ef75a7842 Mon Sep 17 00:00:00 2001 From: Zequan Wu Date: Tue, 12 May 2020 14:07:50 -0700 Subject: Add nomerge function attribute to supress tail merge optimization in simplifyCFG We want to add a way to avoid merging identical calls so as to keep the separate debug-information for those calls. There is also an asan usecase where having this attribute would be beneficial to avoid alternative work-arounds. Here is the link to the feature request: https://bugs.llvm.org/show_bug.cgi?id=42783. `nomerge` is different from `noline`. `noinline` prevents function from inlining at callsites, but `nomerge` prevents multiple identical calls from being merged into one. This patch adds `nomerge` to disable the optimization in IR level. A followup patch will be needed to let backend understands `nomerge` and avoid tail merge at backend. Reviewed By: asbirlea, rnk Differential Revision: https://reviews.llvm.org/D78659 --- llvm/lib/Bitcode/Reader/BitcodeReader.cpp | 2 ++ 1 file changed, 2 insertions(+) (limited to 'llvm/lib/Bitcode/Reader/BitcodeReader.cpp') diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp index f36dab3..6e9ff6e 100644 --- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp +++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp @@ -1442,6 +1442,8 @@ static Attribute::AttrKind getAttrFromCode(uint64_t Code) { return Attribute::NoInline; case bitc::ATTR_KIND_NO_RECURSE: return Attribute::NoRecurse; + case bitc::ATTR_KIND_NO_MERGE: + return Attribute::NoMerge; case bitc::ATTR_KIND_NON_LAZY_BIND: return Attribute::NonLazyBind; case bitc::ATTR_KIND_NON_NULL: -- cgit v1.1