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[X86] Added support for nocf_check attribute for indirect Branch Tracking

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X86 Supports Indirect Branch Tracking (IBT) as part of Control-Flow Enforcement Technology (CET).
IBT instruments ENDBR instructions used to specify valid targets of indirect call / jmp.
The `nocf_check` attribute has two roles in the context of X86 IBT technology:
	1. Appertains to a function - do not add ENDBR instruction at the beginning of the function.
	2. Appertains to a function pointer - do not track the target function of this pointer by adding nocf_check prefix to the indirect-call instruction.

This patch implements `nocf_check` context for Indirect Branch Tracking.
It also auto generates `nocf_check` prefixes before indirect branchs to jump tables that are guarded by range checks.

Differential Revision: https://reviews.llvm.org/D41879

llvm-svn: 327767
This commit is contained in:
Oren Ben Simhon
2018-03-17 13:29:46 +00:00
parent dbcf1bf503
commit fdd72fd522
34 changed files with 302 additions and 76 deletions
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2
llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
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@@ -638,6 +638,8 @@ static uint64_t getAttrKindEncoding(Attribute::AttrKind Kind) {
return bitc::ATTR_KIND_NO_RED_ZONE;
case Attribute::NoReturn:
return bitc::ATTR_KIND_NO_RETURN;
case Attribute::NoCfCheck:
return bitc::ATTR_KIND_NOCF_CHECK;
case Attribute::NoUnwind:
return bitc::ATTR_KIND_NO_UNWIND;
case Attribute::OptimizeForSize: