Author: Pavel Labath Date: 2020-12-22T10:07:47+01:00 New Revision: 8d75d902a955602feb7e2501e34f814ff5630415
URL: https://github.com/llvm/llvm-project/commit/8d75d902a955602feb7e2501e34f814ff5630415 DIFF: https://github.com/llvm/llvm-project/commit/8d75d902a955602feb7e2501e34f814ff5630415.diff LOG: [DebugInfo] Don't use DW_OP_implicit_value for fragments Currently using DW_OP_implicit_value in fragments produces invalid DWARF expressions. (Such a case can occur in complex floats, for example.) This problem manifests itself as a missing DW_OP_piece operation after the last fragment. This happens because the function for printing constant float value skips printing the accompanying DWARF expression, as that would also print DW_OP_stack_value (which is not desirable in this case). However, this also results in DW_OP_piece being skipped. The reason that DW_OP_piece is missing only for the last piece is that the act of printing the next fragment corrects this. However, it does that for the wrong reason -- the code emitting this DW_OP_piece thinks that the previous fragment was missing, and so it thinks that it needs to skip over it in order to be able to print itself. In a simple scenario this works out, but it's likely that in a more complex setup (where some pieces are in fact missing), this logic would go badly wrong. In a simple setup gdb also seems to not mind the fact that the DW_OP_piece is missing, but it would also likely not handle more complex use cases. For this reason, this patch disables the usage of DW_OP_implicit_value in the frament scenario (we will use DW_OP_const*** instead), until we figure out the right way to deal with this. This guarantees that we produce valid expressions, and gdb can handle both kinds of inputs anyway. Differential Revision: https://reviews.llvm.org/D92013 Added: Modified: llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp llvm/test/DebugInfo/X86/implicit_value-double.ll Removed: ################################################################################ diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp index 75b4a2831b0f..6127c503404f 100644 --- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp +++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp @@ -2477,13 +2477,13 @@ void DwarfDebug::emitDebugLocValue(const AsmPrinter &AP, const DIBasicType *BT, DwarfExpr.addExpression(std::move(ExprCursor)); return; } else if (Value.isConstantFP()) { - if (AP.getDwarfVersion() >= 4 && !AP.getDwarfDebug()->tuneForSCE()) { + if (AP.getDwarfVersion() >= 4 && !AP.getDwarfDebug()->tuneForSCE() && + !ExprCursor) { DwarfExpr.addConstantFP(Value.getConstantFP()->getValueAPF(), AP); return; - } else if (Value.getConstantFP() - ->getValueAPF() - .bitcastToAPInt() - .getBitWidth() <= 64 /*bits*/) + } + if (Value.getConstantFP()->getValueAPF().bitcastToAPInt().getBitWidth() <= + 64 /*bits*/) DwarfExpr.addUnsignedConstant( Value.getConstantFP()->getValueAPF().bitcastToAPInt()); else diff --git a/llvm/test/DebugInfo/X86/implicit_value-double.ll b/llvm/test/DebugInfo/X86/implicit_value-double.ll index f205cb9a68ee..956c896b8d34 100644 --- a/llvm/test/DebugInfo/X86/implicit_value-double.ll +++ b/llvm/test/DebugInfo/X86/implicit_value-double.ll @@ -1,8 +1,8 @@ ;; This test checks for emission of DW_OP_implicit_value operation ;; for double type. -; RUN: llc -debugger-tune=gdb -filetype=obj %s -o - | llvm-dwarfdump - | FileCheck %s -; RUN: llc -debugger-tune=lldb -filetype=obj %s -o - | llvm-dwarfdump - | FileCheck %s +; RUN: llc -O0 -debugger-tune=gdb -filetype=obj %s -o - | llvm-dwarfdump - | FileCheck %s --check-prefixes=CHECK,BOTH +; RUN: llc -O0 -debugger-tune=lldb -filetype=obj %s -o - | llvm-dwarfdump - | FileCheck %s --check-prefixes=CHECK,BOTH ; CHECK: .debug_info contents: ; CHECK: DW_TAG_variable @@ -10,7 +10,7 @@ ; CHECK-NEXT: [{{.*}}): DW_OP_implicit_value 0x8 0x1f 0x85 0xeb 0x51 0xb8 0x1e 0x09 0x40) ; CHECK-NEXT: DW_AT_name ("d") -; RUN: llc -debugger-tune=sce -filetype=obj %s -o - | llvm-dwarfdump - | FileCheck %s -check-prefix=SCE-CHECK +; RUN: llc -O0 -debugger-tune=sce -filetype=obj %s -o - | llvm-dwarfdump - | FileCheck %s -check-prefixes=SCE-CHECK,BOTH ; SCE-CHECK: .debug_info contents: ; SCE-CHECK: DW_TAG_variable @@ -18,13 +18,11 @@ ; SCE-CHECK-NEXT: [{{.*}}): DW_OP_constu 0x40091eb851eb851f, DW_OP_stack_value) ; SCE-CHECK-NEXT: DW_AT_name ("d") -;; Generated from: clang -ggdb -O1 -;;int main() { -;; double d = 3.14; -;; printf("dummy\n"); -;; d *= d; -;; return 0; -;;} +;; Using DW_OP_implicit_value for fragments is not currently supported. +; BOTH: DW_TAG_variable +; BOTH-NEXT: DW_AT_location ({{.*}} +; BOTH-NEXT: [{{.*}}): DW_OP_constu 0x4047800000000000, DW_OP_stack_value, DW_OP_piece 0x8, DW_OP_constu 0x4052800000000000, DW_OP_stack_value, DW_OP_piece 0x8) +; BOTH-NEXT: DW_AT_name ("c") ; ModuleID = 'implicit_value-double.c' source_filename = "implicit_value-double.c" @@ -37,6 +35,8 @@ target triple = "x86_64-unknown-linux-gnu" define dso_local i32 @main() local_unnamed_addr #0 !dbg !7 { entry: call void @llvm.dbg.value(metadata double 3.140000e+00, metadata !12, metadata !DIExpression()), !dbg !14 + call void @llvm.dbg.value(metadata double 4.700000e+01, metadata !17, metadata !DIExpression(DW_OP_LLVM_fragment, 0, 64)), !dbg !14 + call void @llvm.dbg.value(metadata double 7.400000e+01, metadata !17, metadata !DIExpression(DW_OP_LLVM_fragment, 64, 64)), !dbg !14 %puts = call i32 @puts(i8* nonnull dereferenceable(1) getelementptr inbounds ([6 x i8], [6 x i8]* @str, i64 0, i64 0)), !dbg !15 call void @llvm.dbg.value(metadata double undef, metadata !12, metadata !DIExpression()), !dbg !14 ret i32 0, !dbg !16 @@ -67,9 +67,11 @@ attributes #2 = { nofree nounwind } !8 = !DISubroutineType(types: !9) !9 = !{!10} !10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed) -!11 = !{!12} +!11 = !{!12, !17} !12 = !DILocalVariable(name: "d", scope: !7, file: !1, line: 2, type: !13) !13 = !DIBasicType(name: "double", size: 64, encoding: DW_ATE_float) !14 = !DILocation(line: 0, scope: !7) !15 = !DILocation(line: 3, column: 2, scope: !7) !16 = !DILocation(line: 5, column: 2, scope: !7) +!17 = !DILocalVariable(name: "c", scope: !7, file: !1, line: 2, type: !18) +!18 = !DIBasicType(name: "complex", size: 128, encoding: DW_ATE_complex_float) _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits