[flang-commits] [flang] 2e5a523 - [flang][debug] Avoid redundant debug data generation for derived types. (#124473)
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Mon Jan 27 11:38:30 PST 2025
Author: Abid Qadeer
Date: 2025-01-27T19:38:24Z
New Revision: 2e5a5237daf82a657561c490845c406e13657311
URL: https://github.com/llvm/llvm-project/commit/2e5a5237daf82a657561c490845c406e13657311
DIFF: https://github.com/llvm/llvm-project/commit/2e5a5237daf82a657561c490845c406e13657311.diff
LOG: [flang][debug] Avoid redundant debug data generation for derived types. (#124473)
Since https://github.com/llvm/llvm-project/pull/122770, we have seen
that compile time have become extremely slow for cyclic derived types.
In #122770, we made the criteria to cache a derived type very strict. As
a result, some types which are safe to cache were also being
re-generated every type they were required. This increased the compile
time and also the size of the debug info.
Please see the description of PR# 122770. We decided that when
processing `t1`, the type generated for `t2` and `t3` were not safe to
cached. But our algorithm also denied caching to `t1` which as top level
type was safe.
```
type t1
type(t2), pointer :: p1
end type
type t2
type(t3), pointer :: p2
end type
type t3
type(t1), pointer :: p3
end type
```
I have tinkered the check a bit so that top level type is always cached.
To detect a top level type, we use a depth counter that get incremented
before call to `convertRecordType` and decremented after it returns.
After this change, the following
[file](https://github.com/fujitsu/compiler-test-suite/blob/main/Fortran/0394/0394_0031.f90)
from Fujitsu get compiled around 40s which is same as it was before
#122770.
The smaller testcase present in issue #124049 takes less than half a
second. I also added check to make sure that duplicate entries of the
`DICompositeType` are not present in the IR.
Fixes #124049 and #123960.
Added:
Modified:
flang/lib/Optimizer/Transforms/DebugTypeGenerator.cpp
flang/lib/Optimizer/Transforms/DebugTypeGenerator.h
flang/test/Integration/debug-cyclic-derived-type-3.f90
Removed:
################################################################################
diff --git a/flang/lib/Optimizer/Transforms/DebugTypeGenerator.cpp b/flang/lib/Optimizer/Transforms/DebugTypeGenerator.cpp
index 555f354521c9b7..cdd30dce183dd5 100644
--- a/flang/lib/Optimizer/Transforms/DebugTypeGenerator.cpp
+++ b/flang/lib/Optimizer/Transforms/DebugTypeGenerator.cpp
@@ -48,7 +48,8 @@ DebugTypeGenerator::DebugTypeGenerator(mlir::ModuleOp m,
mlir::SymbolTable *symbolTable_,
const mlir::DataLayout &dl)
: module(m), symbolTable(symbolTable_), dataLayout{&dl},
- kindMapping(getKindMapping(m)), llvmTypeConverter(m, false, false, dl) {
+ kindMapping(getKindMapping(m)), llvmTypeConverter(m, false, false, dl),
+ derivedTypeDepth(0) {
LLVM_DEBUG(llvm::dbgs() << "DITypeAttr generator\n");
mlir::MLIRContext *context = module.getContext();
@@ -407,7 +408,10 @@ mlir::LLVM::DITypeAttr DebugTypeGenerator::convertRecordType(
/*baseType=*/nullptr, mlir::LLVM::DIFlags::Zero, offset * 8,
/*alignInBits=*/0, elements, /*dataLocation=*/nullptr, /*rank=*/nullptr,
/*allocated=*/nullptr, /*associated=*/nullptr);
- if (canCacheThisType) {
+
+ // derivedTypeDepth == 1 means that it is a top level type which is safe to
+ // cache.
+ if (canCacheThisType || derivedTypeDepth == 1) {
typeCache[Ty] = finalAttr;
} else {
auto iter = typeCache.find(Ty);
@@ -663,7 +667,27 @@ DebugTypeGenerator::convertType(mlir::Type Ty, mlir::LLVM::DIFileAttr fileAttr,
return convertCharacterType(charTy, fileAttr, scope, declOp,
/*hasDescriptor=*/false);
} else if (auto recTy = mlir::dyn_cast_if_present<fir::RecordType>(Ty)) {
- return convertRecordType(recTy, fileAttr, scope, declOp);
+ // For nested derived types like shown below, the call sequence of the
+ // convertRecordType will look something like as follows:
+ // convertRecordType (t1)
+ // convertRecordType (t2)
+ // convertRecordType (t3)
+ // We need to recognize when we are processing the top level type like t1
+ // to make caching decision. The variable `derivedTypeDepth` is used for
+ // this purpose and maintains the current depth of derived type processing.
+ // type t1
+ // type(t2), pointer :: p1
+ // end type
+ // type t2
+ // type(t3), pointer :: p2
+ // end type
+ // type t2
+ // integer a
+ // end type
+ derivedTypeDepth++;
+ auto result = convertRecordType(recTy, fileAttr, scope, declOp);
+ derivedTypeDepth--;
+ return result;
} else if (auto tupleTy = mlir::dyn_cast_if_present<mlir::TupleType>(Ty)) {
return convertTupleType(tupleTy, fileAttr, scope, declOp);
} else if (auto refTy = mlir::dyn_cast_if_present<fir::ReferenceType>(Ty)) {
diff --git a/flang/lib/Optimizer/Transforms/DebugTypeGenerator.h b/flang/lib/Optimizer/Transforms/DebugTypeGenerator.h
index 7daa0af166e697..cc4b5428ee1a9e 100644
--- a/flang/lib/Optimizer/Transforms/DebugTypeGenerator.h
+++ b/flang/lib/Optimizer/Transforms/DebugTypeGenerator.h
@@ -91,6 +91,7 @@ class DebugTypeGenerator {
std::uint64_t lenOffset;
std::uint64_t rankOffset;
std::uint64_t rankSize;
+ int32_t derivedTypeDepth;
llvm::DenseMap<mlir::Type, mlir::LLVM::DITypeAttr> typeCache;
};
diff --git a/flang/test/Integration/debug-cyclic-derived-type-3.f90 b/flang/test/Integration/debug-cyclic-derived-type-3.f90
index ef9aed13cc514c..d91c635576e26b 100644
--- a/flang/test/Integration/debug-cyclic-derived-type-3.f90
+++ b/flang/test/Integration/debug-cyclic-derived-type-3.f90
@@ -1,4 +1,4 @@
-! RUN: %flang_fc1 -emit-llvm -debug-info-kind=standalone %s -o -
+! RUN: %flang_fc1 -emit-llvm -debug-info-kind=standalone %s -o - | FileCheck %s
! mainly test that this program does not cause an assertion failure
! testcase for issue 122024
@@ -17,7 +17,7 @@ module m1
program test
use m1
- type(t1),pointer :: foo
+ type(t1),pointer :: foo, foo2
allocate(foo)
allocate(foo%x1)
allocate(foo%x1%x2)
@@ -30,3 +30,7 @@ subroutine sub1(bar)
use m1
type(t2) :: bar
end subroutine
+
+! Test that file compiles ok and there is only one DICompositeType for "t1".
+!CHECK: !DICompositeType(tag: DW_TAG_structure_type, name: "t1"{{.*}})
+!CHECK-NOT: !DICompositeType(tag: DW_TAG_structure_type, name: "t1"{{.*}})
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