vsk added inline comments.
================
Comment at: lib/CodeGen/CGExpr.cpp:72
+ // Set debug location in order to preserve the scope
+ Alloca->setDebugLoc(Builder.getCurrentDebugLocation());
if (AllocaAddr)
----------------
I think we need to be a bit more careful here. The current debug location
stored in the builder may not be an artificial 0-location. This may cause
non-linear single-stepping behavior. Consider this example:
```
void foo() {
bar();
if (...) {
int var = ...; //< Clang emits an alloca for "var".
}
...
```
The current debug location at the line "int var = ..." would be at line 4. But
the alloca is emitted in the entry block of the function. In the debugger, this
may result in strange single-stepping behavior when stepping into foo(). You
could step to line 4, then line 2, then line 3, then line 4 again.
I think we can avoid that by setting an artificial location on allocas.
================
Comment at: lib/CodeGen/CGExpr.cpp:105
return new llvm::AllocaInst(Ty, CGM.getDataLayout().getAllocaAddrSpace(),
ArraySize, Name, AllocaInsertPt);
}
----------------
Why not apply the location here to cover more cases?
================
Comment at: test/CodeGen/debug-info-preserve-scope.c:11
+
+// CHECK: [[B:%.*]] = alloca i32 {{.*}} !dbg ![[artificialDbgLoc:[0-9]+]]
+// CHECK: store i32 {{.*}} !dbg ![[artificialDbgLoc]]
----------------
Why is "B" captured?
Repository:
rC Clang
https://reviews.llvm.org/D47097
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