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[clang][OpenMP][DebugInfo] Debug support for private variables inside an OpenMP task construct 

Currently variables appearing inside private/firstprivate/lastprivate
clause of openmp task construct are not visible inside lldb debugger.
This is because compiler does not generate debug info for it.

Please consider the testcase debug_private.c attached with patch.

```
   28   #pragma omp task shared(res) private(priv1, priv2) firstprivate(fpriv)
   29       {
   30         priv1 = n;
   31         priv2 = n + 2;
   32         printf("Task n=%d,priv1=%d,priv2=%d,fpriv=%d\n",n,priv1,priv2,fpriv);
   33
-> 34         res = priv1 + priv2 + fpriv + foo(n - 1);
   35       }
   36   #pragma omp taskwait
   37       return res;
(lldb) p priv1
error: <user expression 0>:1:1: use of undeclared identifier 'priv1'
priv1
^
(lldb) p priv2
error: <user expression 1>:1:1: use of undeclared identifier 'priv2'
priv2
^
(lldb) p fpriv
error: <user expression 2>:1:1: use of undeclared identifier 'fpriv'
fpriv
^
```

After the current patch, lldb is able to show the variables

```
(lldb) p priv1
(int) $0 = 10
(lldb) p priv2
(int) $1 = 12
(lldb) p fpriv
(int) $2 = 14
```

Reviewed By: djtodoro

Differential Revision: https://reviews.llvm.org/D114504
This commit is contained in:
Alok Kumar Sharma 2021-11-24 10:38:19 +05:30
parent 6eca1957ee
commit 36cb7477d1
2 changed files with 48 additions and 0 deletions
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3
clang/lib/CodeGen/CGStmtOpenMP.cpp
View File

@ -4510,6 +4510,9 @@ void CodeGenFunction::EmitOMPTaskBasedDirective(
Address Replacement(CGF.Builder.CreateLoad(Pair.second),
CGF.getContext().getDeclAlign(Pair.first));
Scope.addPrivate(Pair.first, [Replacement]() { return Replacement; });
if (auto *DI = CGF.getDebugInfo())
DI->EmitDeclareOfAutoVariable(Pair.first, Pair.second.getPointer(),
CGF.Builder, /*UsePointerValue*/ true);
}
// Adjust mapping for internal locals by mapping actual memory instead of
// a pointer to this memory.

45
clang/test/OpenMP/debug_private.c Normal file
View File

@ -0,0 +1,45 @@
// This testcase checks emission of debug info for variables inside
// private/firstprivate/lastprivate.
// REQUIRES: x86_64-linux
// RUN: %clang_cc1 -debug-info-kind=constructor -x c -verify -triple x86_64-pc-linux-gnu -fopenmp -emit-llvm %s -o - | FileCheck %s
// expected-no-diagnostics
// CHECK: define internal i32 @.omp_task_entry.
// CHECK: call void @llvm.dbg.declare(metadata i32** %.priv.ptr.addr.i, metadata [[PRIV1:![0-9]+]], metadata !DIExpression(DW_OP_deref))
// CHECK: call void @llvm.dbg.declare(metadata i32** %.priv.ptr.addr1.i, metadata [[PRIV2:![0-9]+]], metadata !DIExpression(DW_OP_deref))
// CHECK: call void @llvm.dbg.declare(metadata i32** %.firstpriv.ptr.addr.i, metadata [[FPRIV:![0-9]+]], metadata !DIExpression(DW_OP_deref))
// CHECK: [[PRIV1]] = !DILocalVariable(name: "priv1"
// CHECK: [[PRIV2]] = !DILocalVariable(name: "priv2"
// CHECK: [[FPRIV]] = !DILocalVariable(name: "fpriv"
extern int printf(const char *, ...);
int foo(int n) {
int res, priv1, priv2, fpriv;
fpriv = n + 4;
if (n < 2)
return n;
else {
#pragma omp task shared(res) private(priv1, priv2) firstprivate(fpriv)
{
priv1 = n;
priv2 = n + 2;
printf("Task n=%d,priv1=%d,priv2=%d,fpriv=%d\n", n, priv1, priv2, fpriv);
res = priv1 + priv2 + fpriv + foo(n - 1);
}
#pragma omp taskwait
return res;
}
}
int main() {
int n = 10;
printf("foo(%d) = %d\n", n, foo(n));
return 0;
}