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Debuginfo: Fix nested variables (primarily for CodeView) (#2909)

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We've been going back and forth between GEPs and complex DWARF
expressions based on the context pointer; this goes back to the latter,
as that fixes simple nested variables for CodeView with LLVM >= 6.

I guess it also helps for debuginfos of nested vars with enabled
optimizations.
This commit is contained in:
Martin Kinkelin 2018-11-20 20:44:47 +01:00 • committed by GitHub
parent 78d6fb3bb8
commit 32b6e49a65
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GPG key ID: 4AEE18F83AFDEB23
4 changed files with 34 additions and 54 deletions
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33
gen/nested.cpp
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@ -93,6 +93,21 @@ DValue *DtoNestedVariable(Loc &loc, Type *astype, VarDeclaration *vd,
IF_LOG { Logger::cout() << "casting to: " << *irfunc->frameType << '\n'; }
LLValue *val = DtoBitCast(ctx, frameType);
// Make the DWARF variable address relative to the context pointer (ctx);
// register all ops (offsetting, dereferencing) required to get there in the
// following list.
LLSmallVector<int64_t, 4> dwarfAddrOps;
const auto offsetToNthField = [&val, &dwarfAddrOps](unsigned fieldIndex,
const char *name = "") {
gIR->DBuilder.OpOffset(dwarfAddrOps, val, fieldIndex);
val = DtoGEPi(val, 0, fieldIndex, name);
};
const auto dereference = [&val, &dwarfAddrOps](const char *name = "") {
gIR->DBuilder.OpDeref(dwarfAddrOps);
val = DtoAlignedLoad(val, name);
};
IrLocal *const irLocal = getIrLocal(vd);
const auto vardepth = irLocal->nestedDepth;
const auto funcdepth = irfunc->depth;
@ -111,20 +126,16 @@ DValue *DtoNestedVariable(Loc &loc, Type *astype, VarDeclaration *vd,
} else {
// Load frame pointer and index that...
IF_LOG Logger::println("Lower depth");
val = DtoGEPi(val, 0, vardepth);
offsetToNthField(vardepth);
IF_LOG Logger::cout() << "Frame index: " << *val << '\n';
val = DtoAlignedLoad(
val, (std::string(".frame.") + vdparent->toChars()).c_str());
dereference((std::string(".frame.") + vdparent->toChars()).c_str());
IF_LOG Logger::cout() << "Frame: " << *val << '\n';
}
const auto idx = irLocal->nestedIndex;
assert(idx != -1 && "Nested context not yet resolved for variable.");
LLSmallVector<int64_t, 2> dwarfAddrOps;
LLValue *gep = DtoGEPi(val, 0, idx, vd->toChars());
val = gep;
offsetToNthField(idx, vd->toChars());
IF_LOG {
Logger::cout() << "Addr: " << *val << '\n';
Logger::cout() << "of type: " << *val->getType() << '\n';
@ -135,8 +146,8 @@ DValue *DtoNestedVariable(Loc &loc, Type *astype, VarDeclaration *vd,
// storage of pointer (reference lvalue).
} else if (byref || isRefOrOut) {
val = DtoAlignedLoad(val);
// ref/out variables get a reference-debuginfo-type in EmitLocalVariable();
// pass the GEP as reference lvalue in that case.
// ref/out variables get a reference-debuginfo-type in EmitLocalVariable()
// => don't dereference, use reference lvalue as address
if (!isRefOrOut)
gIR->DBuilder.OpDeref(dwarfAddrOps);
IF_LOG {
@ -147,11 +158,9 @@ DValue *DtoNestedVariable(Loc &loc, Type *astype, VarDeclaration *vd,
if (!skipDIDeclaration && global.params.symdebug) {
#if LDC_LLVM_VER < 500
// Because we are passing a GEP instead of an alloca to
// llvm.dbg.declare, we have to make the address dereference explicit.
gIR->DBuilder.OpDeref(dwarfAddrOps);
#endif
gIR->DBuilder.EmitLocalVariable(gep, vd, nullptr, false,
gIR->DBuilder.EmitLocalVariable(ctx, vd, nullptr, false,
/*forceAsLocal=*/true, false, dwarfAddrOps);
}