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[SanitizerCoverage] Fix types of __stop* and __start* symbols 

If a section is supposed to hold elements of type T, then the
corresponding CreateSecStartEnd()'s Ty parameter represents T*.
Forwarding it to GlobalVariable constructor causes the resulting
GlobalVariable's type to be T*, and its SSA value type to be T**, which
is one indirection too many. This issue is mostly masked by pointer
casts, however, the global variable still gets an incorrect alignment,
which causes SystemZ to choose wrong instructions to access the
section.
This commit is contained in:
Ilya Leoshkevich 2020-07-30 20:08:08 +02:00
parent a4e537d9c4
commit 153df1373e
4 changed files with 12 additions and 13 deletions
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17
llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
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@ -338,25 +338,24 @@ PreservedAnalyses ModuleSanitizerCoveragePass::run(Module &M,
std::pair<Value *, Value *>
ModuleSanitizerCoverage::CreateSecStartEnd(Module &M, const char *Section,
Type *Ty) {
GlobalVariable *SecStart =
new GlobalVariable(M, Ty, false, GlobalVariable::ExternalLinkage, nullptr,
getSectionStart(Section));
GlobalVariable *SecStart = new GlobalVariable(
M, Ty->getPointerElementType(), false, GlobalVariable::ExternalLinkage,
nullptr, getSectionStart(Section));
SecStart->setVisibility(GlobalValue::HiddenVisibility);
GlobalVariable *SecEnd =
new GlobalVariable(M, Ty, false, GlobalVariable::ExternalLinkage,
nullptr, getSectionEnd(Section));
GlobalVariable *SecEnd = new GlobalVariable(
M, Ty->getPointerElementType(), false, GlobalVariable::ExternalLinkage,
nullptr, getSectionEnd(Section));
SecEnd->setVisibility(GlobalValue::HiddenVisibility);
IRBuilder<> IRB(M.getContext());
Value *SecEndPtr = IRB.CreatePointerCast(SecEnd, Ty);
if (!TargetTriple.isOSBinFormatCOFF())
return std::make_pair(IRB.CreatePointerCast(SecStart, Ty), SecEndPtr);
return std::make_pair(SecStart, SecEnd);
// Account for the fact that on windows-msvc __start_* symbols actually
// point to a uint64_t before the start of the array.
auto SecStartI8Ptr = IRB.CreatePointerCast(SecStart, Int8PtrTy);
auto GEP = IRB.CreateGEP(Int8Ty, SecStartI8Ptr,
ConstantInt::get(IntptrTy, sizeof(uint64_t)));
return std::make_pair(IRB.CreatePointerCast(GEP, Ty), SecEndPtr);
return std::make_pair(IRB.CreatePointerCast(GEP, Ty), SecEnd);
}
Function *ModuleSanitizerCoverage::CreateInitCallsForSections(

2
llvm/test/Instrumentation/SanitizerCoverage/inline-8bit-counters.ll
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@ -12,4 +12,4 @@ entry:
; CHECK: store i8 %1, i8* getelementptr inbounds ([1 x i8], [1 x i8]* @__sancov_gen_, i64 0, i64 0), align 1, !nosanitize
ret void
}
; CHECK: call void @__sanitizer_cov_8bit_counters_init(i8* bitcast (i8** @__start___sancov_cntrs to i8*), i8* bitcast (i8** @__stop___sancov_cntrs to i8*))
; CHECK: call void @__sanitizer_cov_8bit_counters_init(i8* @__start___sancov_cntrs, i8* @__stop___sancov_cntrs)

2
llvm/test/Instrumentation/SanitizerCoverage/inline-bool-flag.ll
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@ -20,4 +20,4 @@ define void @foo() {
entry:
ret void
}
; CHECK: call void @__sanitizer_cov_bool_flag_init(i1* bitcast (i1** @__start___sancov_bools to i1*), i1* bitcast (i1** @__stop___sancov_bools to i1*))
; CHECK: call void @__sanitizer_cov_bool_flag_init(i1* @__start___sancov_bools, i1* @__stop___sancov_bools)

4
llvm/test/Instrumentation/SanitizerCoverage/tracing.ll
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@ -74,7 +74,7 @@ lj:
; CHECK_PC_GUARD: call void @longjmp
; CHECK_PC_GUARD: unreachable
; CHECK_PC_GUARD: call void @__sanitizer_cov_trace_pc_guard_init(i32* bitcast (i32** @__start___sancov_guards to i32*), i32* bitcast (i32** @__stop___sancov_guards to i32*))
; CHECK_PC_GUARD: call void @__sanitizer_cov_trace_pc_guard_init(i32* @__start___sancov_guards, i32* @__stop___sancov_guards)
; CHECK_PC_GUARD_DARWIN-LABEL: define void @foo
; CHECK_PC_GUARD_DARWIN: call void @__sanitizer_cov_trace_pc_guard
@ -82,4 +82,4 @@ lj:
; CHECK_PC_GUARD_DARWIN: call void @__sanitizer_cov_trace_pc_guard
; CHECK_PC_GUARD_DARWIN-NOT: call void @__sanitizer_cov_trace_pc
; CHECK_PC_GUARD_DARWIN: ret void
; CHECK_PC_GUARD_DARWIN: call void @__sanitizer_cov_trace_pc_guard_init(i32* bitcast (i32** @"\01section$start$__DATA$__sancov_guards" to i32*), i32* bitcast (i32** @"\01section$end$__DATA$__sancov_guards" to i32*))
; CHECK_PC_GUARD_DARWIN: call void @__sanitizer_cov_trace_pc_guard_init(i32* @"\01section$start$__DATA$__sancov_guards", i32* @"\01section$end$__DATA$__sancov_guards")