[llvm] 75f3bee - [Debug-Info] make DIE attributes generation under strict DWARF control

[Chen Zheng via llvm-commits]

Author: Chen Zheng
Date: 2021-05-13T20:34:07-04:00
New Revision: 75f3beeedf6343e2ce1e8143e0d037d96cdab0b2

URL: https://github.com/llvm/llvm-project/commit/75f3beeedf6343e2ce1e8143e0d037d96cdab0b2
DIFF: https://github.com/llvm/llvm-project/commit/75f3beeedf6343e2ce1e8143e0d037d96cdab0b2.diff

LOG: [Debug-Info] make DIE attributes generation under strict DWARF control

Reviewed By: dblaikie

Differential Revision: https://reviews.llvm.org/D101024

Added: 
    

Modified: 
    llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
    llvm/test/DebugInfo/PowerPC/strict-dwarf.ll

Removed: 
    


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diff  --git a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
index aca831a535a19..75bc3de14d61c 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
@@ -18,6 +18,7 @@
 #include "llvm/ADT/Optional.h"
 #include "llvm/CodeGen/AsmPrinter.h"
 #include "llvm/CodeGen/DIE.h"
+#include "llvm/Target/TargetMachine.h"
 #include <string>
 
 namespace llvm {
@@ -79,6 +80,15 @@ class DwarfUnit : public DIEUnit {
   template <typename T>
   void addAttribute(DIEValueList &Die, dwarf::Attribute Attribute,
                     dwarf::Form Form, T &&Value) {
+    // For strict DWARF mode, only generate attributes available to current
+    // DWARF version.
+    // Attribute 0 is used when emitting form-encoded values in blocks, which
+    // don't have attributes (only forms) so we cannot detect their DWARF
+    // version compatibility here and assume they are compatible.
+    if (Attribute != 0 && Asm->TM.Options.DebugStrictDwarf &&
+        DD->getDwarfVersion() < dwarf::AttributeVersion(Attribute))
+      return;
+
     Die.addValue(DIEValueAllocator,
                  DIEValue(Attribute, Form, std::forward<T>(Value)));
   }

diff  --git a/llvm/test/DebugInfo/PowerPC/strict-dwarf.ll b/llvm/test/DebugInfo/PowerPC/strict-dwarf.ll
index b64fd426e8eab..02590955262ff 100644
--- a/llvm/test/DebugInfo/PowerPC/strict-dwarf.ll
+++ b/llvm/test/DebugInfo/PowerPC/strict-dwarf.ll
@@ -2,16 +2,30 @@
 ; RUN:   llvm-dwarfdump -debug-info - | FileCheck %s
 ; RUN: llc -filetype=obj -mtriple=powerpc64le-unknown-linux-gnu \
 ; RUN:   -strict-dwarf=true < %s | llvm-dwarfdump -debug-info - | \
-; RUN:   FileCheck %s
+; RUN:   FileCheck %s -check-prefix=STRICT
 
-; FIXME: when -strict-dwarf=true is specified, we should check "STRICT" to tell
-; that with DWARF 4, we should not generate DWARF 5 attribute DW_AT_noreturn and
-; DW_AT_alignment.
+; We also check that with/without -strict-dwarf=true, the location attribute
+; is not changed. The location attribute adding will call DwarfUnit::addUInt()
+; which contains a attribute 0, we want to make sure the strict-dwarf handling
+; is also right for attribute 0.
+; For this case, the location attribute adding is for global variable @_ZL3var
+; and the call chain to addUInt() is:
+; 1: DwarfCompileUnit::addLocationAttribute()
+; 2: DwarfUnit::addOpAddress()
+; 3: DwarfUnit::addUInt()
+; 4: addUInt(Block, (dwarf::Attribute)0, Form, Integer);
 
+; CHECK: DW_AT_name      ("var")
+; CHECK-NOT: DW_TAG_
 ; CHECK: DW_AT_alignment
+; CHECK: DW_AT_location  (DW_OP_addr 0x0)
 ; CHECK: DW_AT_noreturn
-; STRICT-NOT: DW_AT_noreturn
+;
+; STRICT: DW_AT_name      ("var")
 ; STRICT-NOT: DW_AT_alignment
+; STRICT-NOT: DW_TAG_
+; STRICT: DW_AT_location  (DW_OP_addr 0x0)
+; STRICT-NOT: DW_AT_noreturn
 
 @_ZL3var = internal global i32 0, align 16, !dbg !0