Simplify codegen and debug info generation for block context parameters.

The exisiting code goes out of its way to put block parameters into an
alloca only at -O0, and then describes the funciton argument with a
dbg.declare, which is undocumented in the LLVM-CFE contract and does
not actually behave as intended after LLVM r642022.

This patch just generates the alloca unconditionally, the mem2reg pass
will eliminate it at -O1 and up anyway and points the dbg.declare to
the alloca as intended (which mem2reg will then correctly rewrite into
a dbg.value).

rdar://problem/35043980

Differential Revision: https://reviews.llvm.org/D39305

llvm-svn: 316684

1 files changed, 4 insertions, 12 deletions

diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index a73e4a98b3c..3e4acd208f6 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -3694,9 +3694,9 @@ bool operator<(const BlockLayoutChunk &l, const BlockLayoutChunk &r) {
 }
 
 void CGDebugInfo::EmitDeclareOfBlockLiteralArgVariable(const CGBlockInfo &block,
-                                                       llvm::Value *Arg,
+                                                       StringRef Name,
                                                        unsigned ArgNo,
-                                                       llvm::Value *LocalAddr,
+                                                       llvm::AllocaInst *Alloca,
                                                        CGBuilderTy &Builder) {
   assert(DebugKind >= codegenoptions::LimitedDebugInfo);
   ASTContext &C = CGM.getContext();
@@ -3828,19 +3828,11 @@ void CGDebugInfo::EmitDeclareOfBlockLiteralArgVariable(const CGBlockInfo &block,
 
   // Create the descriptor for the parameter.
   auto *debugVar = DBuilder.createParameterVariable(
-      scope, Arg->getName(), ArgNo, tunit, line, type,
+      scope, Name, ArgNo, tunit, line, type,
       CGM.getLangOpts().Optimize, flags);
 
-  if (LocalAddr) {
-    // Insert an llvm.dbg.value into the current block.
-    DBuilder.insertDbgValueIntrinsic(
-        LocalAddr, debugVar, DBuilder.createExpression(),
-        llvm::DebugLoc::get(line, column, scope, CurInlinedAt),
-        Builder.GetInsertBlock());
-  }
-
   // Insert an llvm.dbg.declare into the current block.
-  DBuilder.insertDeclare(Arg, debugVar, DBuilder.createExpression(),
+  DBuilder.insertDeclare(Alloca, debugVar, DBuilder.createExpression(),
                          llvm::DebugLoc::get(line, column, scope, CurInlinedAt),
                          Builder.GetInsertBlock());
 }