r305312 - Align definition of DW_OP_plus with DWARF spec [2/3]

[Florian Hahn via cfe-commits]

Author: fhahn
Date: Tue Jun 13 13:06:15 2017
New Revision: 305312

URL: http://llvm.org/viewvc/llvm-project?rev=305312&view=rev
Log:
Align definition of DW_OP_plus with DWARF spec [2/3]

Summary:
This patch is part of 3 patches that together form a single patch, but must be introduced in stages in order not to break things.
 
The way that LLVM interprets DW_OP_plus in DIExpression nodes is basically that of the DW_OP_plus_uconst operator since LLVM expects an unsigned constant operand. This unnecessarily restricts the DW_OP_plus operator, preventing it from being used to describe the evaluation of runtime values on the expression stack. These patches try to align the semantics of DW_OP_plus and DW_OP_minus with that of the DWARF definition, which pops two elements off the expression stack, performs the operation and pushes the result back on the stack.
 
This is done in three stages:
	•	The first patch (LLVM) adds support for DW_OP_plus_uconst and changes all uses (and tests) of DW_OP_plus to use DW_OP_plus_uconst.
 
	•	The second patch (Clang) contains changes to use DW_OP_plus_uconst instead of DW_OP_plus.
 
	•	The third patch (LLVM) changes the semantics of DW_OP_plus to be in line with it’s DWARF meaning. It also does this for DW_OP_minus.

Patch by Sander de Smalen.

Reviewers: echristo, pcc, aprantl

Reviewed By: aprantl

Subscribers: aprantl, cfe-commits

Differential Revision: https://reviews.llvm.org/D33893

Modified:
    cfe/trunk/lib/CodeGen/CGDebugInfo.cpp

Modified: cfe/trunk/lib/CodeGen/CGDebugInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGDebugInfo.cpp?rev=305312&r1=305311&r2=305312&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGDebugInfo.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGDebugInfo.cpp Tue Jun 13 13:06:15 2017
@@ -3490,13 +3490,13 @@ void CGDebugInfo::EmitDeclare(const VarD
     if (VD->hasAttr<BlocksAttr>()) {
       // Here, we need an offset *into* the alloca.
       CharUnits offset = CharUnits::fromQuantity(32);
-      Expr.push_back(llvm::dwarf::DW_OP_plus);
+      Expr.push_back(llvm::dwarf::DW_OP_plus_uconst);
       // offset of __forwarding field
       offset = CGM.getContext().toCharUnitsFromBits(
           CGM.getTarget().getPointerWidth(0));
       Expr.push_back(offset.getQuantity());
       Expr.push_back(llvm::dwarf::DW_OP_deref);
-      Expr.push_back(llvm::dwarf::DW_OP_plus);
+      Expr.push_back(llvm::dwarf::DW_OP_plus_uconst);
       // offset of x field
       offset = CGM.getContext().toCharUnitsFromBits(XOffset);
       Expr.push_back(offset.getQuantity());
@@ -3605,17 +3605,17 @@ void CGDebugInfo::EmitDeclareOfBlockDecl
 
   SmallVector<int64_t, 9> addr;
   addr.push_back(llvm::dwarf::DW_OP_deref);
-  addr.push_back(llvm::dwarf::DW_OP_plus);
+  addr.push_back(llvm::dwarf::DW_OP_plus_uconst);
   addr.push_back(offset.getQuantity());
   if (isByRef) {
     addr.push_back(llvm::dwarf::DW_OP_deref);
-    addr.push_back(llvm::dwarf::DW_OP_plus);
+    addr.push_back(llvm::dwarf::DW_OP_plus_uconst);
     // offset of __forwarding field
     offset =
         CGM.getContext().toCharUnitsFromBits(target.getPointerSizeInBits(0));
     addr.push_back(offset.getQuantity());
     addr.push_back(llvm::dwarf::DW_OP_deref);
-    addr.push_back(llvm::dwarf::DW_OP_plus);
+    addr.push_back(llvm::dwarf::DW_OP_plus_uconst);
     // offset of x field
     offset = CGM.getContext().toCharUnitsFromBits(XOffset);
     addr.push_back(offset.getQuantity());