[llvm] Fix AsmWriter to account for dynamic bit offsets (PR #146704)

[Tom Tromey via llvm-commits]

https://github.com/tromey created https://github.com/llvm/llvm-project/pull/146704

PR #141106 changed the debug metadata to allow dynamic bit offsets and sizes.  In that patch, I forgot to update AsmWriter to handle this case.

This patch corrects the oversight.

>From d40e3ef912a921dfd39fdce1386de4d2ad5b4e5b Mon Sep 17 00:00:00 2001
From: Tom Tromey <tromey at adacore.com>
Date: Tue, 1 Jul 2025 14:17:27 -0600
Subject: [PATCH] Fix AsmWriter to account for dynamic bit offsets

PR #141106 changed the debug metadata to allow dynamic bit offsets and
sizes.  In that patch, I forgot to update AsmWriter to handle this
case.

This patch corrects the oversight.
---
 llvm/lib/IR/AsmWriter.cpp                   | 32 +++++++++++++--------
 llvm/test/DebugInfo/X86/dynamic-bitfield.ll |  2 +-
 2 files changed, 21 insertions(+), 13 deletions(-)

diff --git a/llvm/lib/IR/AsmWriter.cpp b/llvm/lib/IR/AsmWriter.cpp
index af268b4fc6941..029246e375aa4 100644
--- a/llvm/lib/IR/AsmWriter.cpp
+++ b/llvm/lib/IR/AsmWriter.cpp
@@ -2226,13 +2226,14 @@ static void writeDIEnumerator(raw_ostream &Out, const DIEnumerator *N,
 }
 
 static void writeDIBasicType(raw_ostream &Out, const DIBasicType *N,
-                             AsmWriterContext &) {
+                             AsmWriterContext &WriterCtx) {
   Out << "!DIBasicType(";
-  MDFieldPrinter Printer(Out);
+  MDFieldPrinter Printer(Out, WriterCtx);
   if (N->getTag() != dwarf::DW_TAG_base_type)
     Printer.printTag(N);
   Printer.printString("name", N->getName());
-  Printer.printInt("size", N->getSizeInBits());
+  if (N->getRawSizeInBits())
+    Printer.printMetadata("size", N->getRawSizeInBits());
   Printer.printInt("align", N->getAlignInBits());
   Printer.printDwarfEnum("encoding", N->getEncoding(),
                          dwarf::AttributeEncodingString);
@@ -2242,13 +2243,14 @@ static void writeDIBasicType(raw_ostream &Out, const DIBasicType *N,
 }
 
 static void writeDIFixedPointType(raw_ostream &Out, const DIFixedPointType *N,
-                                  AsmWriterContext &) {
+                                  AsmWriterContext &WriterCtx) {
   Out << "!DIFixedPointType(";
-  MDFieldPrinter Printer(Out);
+  MDFieldPrinter Printer(Out, WriterCtx);
   if (N->getTag() != dwarf::DW_TAG_base_type)
     Printer.printTag(N);
   Printer.printString("name", N->getName());
-  Printer.printInt("size", N->getSizeInBits());
+  if (N->getRawSizeInBits())
+    Printer.printMetadata("size", N->getRawSizeInBits());
   Printer.printInt("align", N->getAlignInBits());
   Printer.printDwarfEnum("encoding", N->getEncoding(),
                          dwarf::AttributeEncodingString);
@@ -2275,7 +2277,8 @@ static void writeDIStringType(raw_ostream &Out, const DIStringType *N,
   Printer.printMetadata("stringLengthExpression", N->getRawStringLengthExp());
   Printer.printMetadata("stringLocationExpression",
                         N->getRawStringLocationExp());
-  Printer.printInt("size", N->getSizeInBits());
+  if (N->getRawSizeInBits())
+    Printer.printMetadata("size", N->getRawSizeInBits());
   Printer.printInt("align", N->getAlignInBits());
   Printer.printDwarfEnum("encoding", N->getEncoding(),
                          dwarf::AttributeEncodingString);
@@ -2293,9 +2296,11 @@ static void writeDIDerivedType(raw_ostream &Out, const DIDerivedType *N,
   Printer.printInt("line", N->getLine());
   Printer.printMetadata("baseType", N->getRawBaseType(),
                         /* ShouldSkipNull */ false);
-  Printer.printInt("size", N->getSizeInBits());
+  if (N->getRawSizeInBits())
+    Printer.printMetadata("size", N->getRawSizeInBits());
   Printer.printInt("align", N->getAlignInBits());
-  Printer.printInt("offset", N->getOffsetInBits());
+  if (N->getRawOffsetInBits())
+    Printer.printMetadata("offset", N->getRawOffsetInBits());
   Printer.printDIFlags("flags", N->getFlags());
   Printer.printMetadata("extraData", N->getRawExtraData());
   if (const auto &DWARFAddressSpace = N->getDWARFAddressSpace())
@@ -2323,7 +2328,8 @@ static void writeDISubrangeType(raw_ostream &Out, const DISubrangeType *N,
   Printer.printMetadata("scope", N->getRawScope());
   Printer.printMetadata("file", N->getRawFile());
   Printer.printInt("line", N->getLine());
-  Printer.printInt("size", N->getSizeInBits());
+  if (N->getRawSizeInBits())
+    Printer.printMetadata("size", N->getRawSizeInBits());
   Printer.printInt("align", N->getAlignInBits());
   Printer.printDIFlags("flags", N->getFlags());
   Printer.printMetadata("baseType", N->getRawBaseType(),
@@ -2345,9 +2351,11 @@ static void writeDICompositeType(raw_ostream &Out, const DICompositeType *N,
   Printer.printMetadata("file", N->getRawFile());
   Printer.printInt("line", N->getLine());
   Printer.printMetadata("baseType", N->getRawBaseType());
-  Printer.printInt("size", N->getSizeInBits());
+  if (N->getRawSizeInBits())
+    Printer.printMetadata("size", N->getRawSizeInBits());
   Printer.printInt("align", N->getAlignInBits());
-  Printer.printInt("offset", N->getOffsetInBits());
+  if (N->getRawOffsetInBits())
+    Printer.printMetadata("offset", N->getRawOffsetInBits());
   Printer.printInt("num_extra_inhabitants", N->getNumExtraInhabitants());
   Printer.printDIFlags("flags", N->getFlags());
   Printer.printMetadata("elements", N->getRawElements());
diff --git a/llvm/test/DebugInfo/X86/dynamic-bitfield.ll b/llvm/test/DebugInfo/X86/dynamic-bitfield.ll
index eda4ff0f8f6d1..320560172c28a 100644
--- a/llvm/test/DebugInfo/X86/dynamic-bitfield.ll
+++ b/llvm/test/DebugInfo/X86/dynamic-bitfield.ll
@@ -1,4 +1,4 @@
-; RUN: llc -mtriple=x86_64 -O0 -filetype=obj -o - %s | llvm-dwarfdump -v -debug-info - | FileCheck %s
+; RUN: llvm-as < %s | llvm-dis | llc -mtriple=x86_64 -O0 -filetype=obj -o - | llvm-dwarfdump -v -debug-info - | FileCheck %s
 
 ; A basic test of using a DIExpression for DW_AT_data_bit_offset and
 ; DW_AT_bit_size.