Add LLVM IR debug info support for Fortran COMMON blocks
COMMON blocks are a feature of Fortran that has no direct analog in C languages, but they are similar to data sections in assembly language programming. A COMMON block is a named area of memory that holds a collection of variables. Fortran subprograms may map the COMMON block memory area to their own, possibly distinct, non-empty list of variables. A Fortran COMMON block might look like the following example.
COMMON /ALPHA/ I, J
For this construct, the compiler generates a new scope-like DI construct (!DICommonBlock) into which variables (see I, J above) can be placed. As the common block implies a range of storage with global lifetime, the !DICommonBlock refers to a !DIGlobalVariable. The Fortran variable that comprise the COMMON block are also linked via metadata to offsets within the global variable that stands for the entire common block.
@alpha_ = common global %alphabytes_ zeroinitializer, align 64, !dbg !27, !dbg !30, !dbg !33
!14 = distinct !DISubprogram(…)
!20 = distinct !DICommonBlock(scope: !14, declaration: !25, name: "alpha")
!25 = distinct !DIGlobalVariable(scope: !20, name: "common alpha", type: !24)
!27 = !DIGlobalVariableExpression(var: !25, expr: !DIExpression())
!29 = distinct !DIGlobalVariable(scope: !20, name: "i", file: !3, type: !28)
!30 = !DIGlobalVariableExpression(var: !29, expr: !DIExpression())
!31 = distinct !DIGlobalVariable(scope: !20, name: "j", file: !3, type: !28)
!32 = !DIExpression(DW_OP_plus_uconst, 4)
!33 = !DIGlobalVariableExpression(var: !31, expr: !32)
The DWARF generated for this is as follows.
DW_TAG_common_block:
DW_AT_name: alpha
DW_AT_location: @alpha_+0
DW_TAG_variable:
DW_AT_name: common alpha
DW_AT_type: array of 8 bytes
DW_AT_location: @alpha_+0
DW_TAG_variable:
DW_AT_name: i
DW_AT_type: integer*4
DW_AT_location: @Alpha+0
DW_TAG_variable:
DW_AT_name: j
DW_AT_type: integer*4
DW_AT_location: @Alpha+4
Patch by Eric Schweitz!
Differential Revision: https://reviews.llvm.org/D54327
llvm-svn: 357934
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
index fbb7a57..c1e8ffe 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -123,7 +123,9 @@
// Construct the context before querying for the existence of the DIE in
// case such construction creates the DIE.
- DIE *ContextDIE = getOrCreateContextDIE(GVContext);
+ auto *CB = GVContext ? dyn_cast<DICommonBlock>(GVContext) : nullptr;
+ DIE *ContextDIE = CB ? getOrCreateCommonBlock(CB, GlobalExprs)
+ : getOrCreateContextDIE(GVContext);
// Add to map.
DIE *VariableDIE = &createAndAddDIE(GV->getTag(), *ContextDIE, GV);
@@ -166,6 +168,13 @@
addTemplateParams(*VariableDIE, DINodeArray(TP));
// Add location.
+ addLocationAttribute(VariableDIE, GV, GlobalExprs);
+
+ return VariableDIE;
+}
+
+void DwarfCompileUnit::addLocationAttribute(
+ DIE *VariableDIE, const DIGlobalVariable *GV, ArrayRef<GlobalExpr> GlobalExprs) {
bool addToAccelTable = false;
DIELoc *Loc = nullptr;
Optional<unsigned> NVPTXAddressSpace;
@@ -288,8 +297,25 @@
DD->useAllLinkageNames())
DD->addAccelName(*CUNode, GV->getLinkageName(), *VariableDIE);
}
+}
- return VariableDIE;
+DIE *DwarfCompileUnit::getOrCreateCommonBlock(
+ const DICommonBlock *CB, ArrayRef<GlobalExpr> GlobalExprs) {
+ // Construct the context before querying for the existence of the DIE in case
+ // such construction creates the DIE.
+ DIE *ContextDIE = getOrCreateContextDIE(CB->getScope());
+
+ if (DIE *NDie = getDIE(CB))
+ return NDie;
+ DIE &NDie = createAndAddDIE(dwarf::DW_TAG_common_block, *ContextDIE, CB);
+ StringRef Name = CB->getName().empty() ? "_BLNK_" : CB->getName();
+ addString(NDie, dwarf::DW_AT_name, Name);
+ addGlobalName(Name, NDie, CB->getScope());
+ if (CB->getFile())
+ addSourceLine(NDie, CB->getLineNo(), CB->getFile());
+ if (DIGlobalVariable *V = CB->getDecl())
+ getCU().addLocationAttribute(&NDie, V, GlobalExprs);
+ return &NDie;
}
void DwarfCompileUnit::addRange(RangeSpan Range) {