[llvm] Allow 128-bit discriminants in DWARF variants (PR #125578)
Tom Tromey via llvm-commits
llvm-commits at lists.llvm.org
Tue Feb 4 12:20:59 PST 2025
https://github.com/tromey updated https://github.com/llvm/llvm-project/pull/125578
>From 10c4eb2f8af8dfc5d3f0920987d250b3c8e0e138 Mon Sep 17 00:00:00 2001
From: Tom Tromey <tromey at adacore.com>
Date: Mon, 3 Feb 2025 13:01:17 -0700
Subject: [PATCH] Allow 128-bit discriminants in DWARF variants
If a variant part has a 128-bit discriminator, then
DwarfUnit::constructTypeDIE will assert. This patch fixes the problem
by allowing any size of integer to be used here. This is largely
accomplished by moving part of DwarfUnit::addConstantValue to a new
method.
Fixes #119655
---
llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp | 64 +++++++++++--------
llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h | 8 +++
.../DebugInfo/Generic/discriminated-union.ll | 4 +-
3 files changed, 49 insertions(+), 27 deletions(-)
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
index 0a8a1ad38c959f..46ea5fed70b65b 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
@@ -232,6 +232,42 @@ void DwarfUnit::addUInt(DIEValueList &Block, dwarf::Form Form,
addUInt(Block, (dwarf::Attribute)0, Form, Integer);
}
+void DwarfUnit::addIntAsBlock(DIE &Die, dwarf::Attribute Attribute, const APInt &Val) {
+ DIEBlock *Block = new (DIEValueAllocator) DIEBlock;
+
+ // Get the raw data form of the large APInt.
+ const uint64_t *Ptr64 = Val.getRawData();
+
+ int NumBytes = Val.getBitWidth() / 8; // 8 bits per byte.
+ bool LittleEndian = Asm->getDataLayout().isLittleEndian();
+
+ // Output the constant to DWARF one byte at a time.
+ for (int i = 0; i < NumBytes; i++) {
+ uint8_t c;
+ if (LittleEndian)
+ c = Ptr64[i / 8] >> (8 * (i & 7));
+ else
+ c = Ptr64[(NumBytes - 1 - i) / 8] >> (8 * ((NumBytes - 1 - i) & 7));
+ addUInt(*Block, dwarf::DW_FORM_data1, c);
+ }
+
+ addBlock(Die, Attribute, Block);
+}
+
+void DwarfUnit::addInt(DIE &Die, dwarf::Attribute Attribute,
+ const APInt &Val, bool Unsigned) {
+ unsigned CIBitWidth = Val.getBitWidth();
+ if (CIBitWidth <= 64) {
+ if (Unsigned)
+ addUInt(Die, Attribute, std::nullopt, Val.getZExtValue());
+ else
+ addSInt(Die, Attribute, std::nullopt, Val.getSExtValue());
+ return;
+ }
+
+ addIntAsBlock(Die, Attribute, Val);
+}
+
void DwarfUnit::addSInt(DIEValueList &Die, dwarf::Attribute Attribute,
std::optional<dwarf::Form> Form, int64_t Integer) {
if (!Form)
@@ -484,25 +520,7 @@ void DwarfUnit::addConstantValue(DIE &Die, const APInt &Val, bool Unsigned) {
return;
}
- DIEBlock *Block = new (DIEValueAllocator) DIEBlock;
-
- // Get the raw data form of the large APInt.
- const uint64_t *Ptr64 = Val.getRawData();
-
- int NumBytes = Val.getBitWidth() / 8; // 8 bits per byte.
- bool LittleEndian = Asm->getDataLayout().isLittleEndian();
-
- // Output the constant to DWARF one byte at a time.
- for (int i = 0; i < NumBytes; i++) {
- uint8_t c;
- if (LittleEndian)
- c = Ptr64[i / 8] >> (8 * (i & 7));
- else
- c = Ptr64[(NumBytes - 1 - i) / 8] >> (8 * ((NumBytes - 1 - i) & 7));
- addUInt(*Block, dwarf::DW_FORM_data1, c);
- }
-
- addBlock(Die, dwarf::DW_AT_const_value, Block);
+ addIntAsBlock(Die, dwarf::DW_AT_const_value, Val);
}
void DwarfUnit::addLinkageName(DIE &Die, StringRef LinkageName) {
@@ -972,12 +990,8 @@ void DwarfUnit::constructTypeDIE(DIE &Buffer, const DICompositeType *CTy) {
DIE &Variant = createAndAddDIE(dwarf::DW_TAG_variant, Buffer);
if (const ConstantInt *CI =
dyn_cast_or_null<ConstantInt>(DDTy->getDiscriminantValue())) {
- if (DD->isUnsignedDIType(Discriminator->getBaseType()))
- addUInt(Variant, dwarf::DW_AT_discr_value, std::nullopt,
- CI->getZExtValue());
- else
- addSInt(Variant, dwarf::DW_AT_discr_value, std::nullopt,
- CI->getSExtValue());
+ addInt(Variant, dwarf::DW_AT_discr_value, CI->getValue(),
+ DD->isUnsignedDIType(Discriminator->getBaseType()));
}
constructMemberDIE(Variant, DDTy);
} else {
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
index 163205378fb4b6..9ddd6f8c14175b 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
@@ -167,6 +167,10 @@ class DwarfUnit : public DIEUnit {
void addSInt(DIELoc &Die, std::optional<dwarf::Form> Form, int64_t Integer);
+ /// Add an integer attribute data and value; value may be any width.
+ void addInt(DIE &Die, dwarf::Attribute Attribute, const APInt &Integer,
+ bool Unsigned);
+
/// Add a string attribute data and value.
///
/// We always emit a reference to the string pool instead of immediate
@@ -334,6 +338,10 @@ class DwarfUnit : public DIEUnit {
void emitCommonHeader(bool UseOffsets, dwarf::UnitType UT);
private:
+ /// A helper to add a wide integer constant to a DIE using a block
+ /// form.
+ void addIntAsBlock(DIE &Die, dwarf::Attribute Attribute, const APInt &Val);
+
void constructTypeDIE(DIE &Buffer, const DIBasicType *BTy);
void constructTypeDIE(DIE &Buffer, const DIStringType *BTy);
void constructTypeDIE(DIE &Buffer, const DIDerivedType *DTy);
diff --git a/llvm/test/DebugInfo/Generic/discriminated-union.ll b/llvm/test/DebugInfo/Generic/discriminated-union.ll
index d267d9b029e950..592f2152ae6820 100644
--- a/llvm/test/DebugInfo/Generic/discriminated-union.ll
+++ b/llvm/test/DebugInfo/Generic/discriminated-union.ll
@@ -22,7 +22,7 @@
; CHECK: DW_AT_alignment
; CHECK: DW_AT_data_member_location [DW_FORM_data1] (0x00)
; CHECK: DW_TAG_variant
-; CHECK: DW_AT_discr_value [DW_FORM_data1] (0x00)
+; CHECK: DW_AT_discr_value [DW_FORM_block1] (<0x10> 00 00 00 00 00 00 00 00 01 00 00 00 00 00 00 00 )
; CHECK: DW_TAG_member
; CHECK: DW_AT_type
; CHECK: DW_AT_alignment
@@ -71,7 +71,7 @@ attributes #0 = { nounwind uwtable }
!21 = !DIBasicType(name: "u8", size: 8, encoding: DW_ATE_unsigned)
!22 = !DIDerivedType(tag: DW_TAG_member, name: "__1", scope: !18, file: !7, baseType: !23, size: 64, align: 64)
!23 = !DIDerivedType(tag: DW_TAG_pointer_type, name: "&u8", baseType: !21, size: 64, align: 64)
-!24 = !DIDerivedType(tag: DW_TAG_member, scope: !14, file: !7, baseType: !25, size: 128, align: 64, extraData: i64 0)
+!24 = !DIDerivedType(tag: DW_TAG_member, scope: !14, file: !7, baseType: !25, size: 128, align: 64, extraData: i128 18446744073709551616)
!25 = !DICompositeType(tag: DW_TAG_structure_type, name: "Nope", scope: !12, file: !7, size: 128, align: 64, elements: !4, identifier: "7ce1efff6b82281ab9ceb730566e7e20::Nope")
!27 = !DIBasicType(name: "u64", size: 64, encoding: DW_ATE_unsigned)
!28 = !DIExpression()
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