[llvm] ec50e10 - DebugInfo: Hash DW_OP_convert in loclists when using Split DWARF

[David Blaikie via llvm-commits]

Author: David Blaikie
Date: 2020-02-04T19:25:47-08:00
New Revision: ec50e10db437d935a3faee0d72fd5b80d49682ab

URL: https://github.com/llvm/llvm-project/commit/ec50e10db437d935a3faee0d72fd5b80d49682ab
DIFF: https://github.com/llvm/llvm-project/commit/ec50e10db437d935a3faee0d72fd5b80d49682ab.diff

LOG: DebugInfo: Hash DW_OP_convert in loclists when using Split DWARF

Originally committed in: 1ced28cbe75ff81f35ac2c71e941041eb3afcd00
            Reverted in: f75301d16d444d8cb6810d679290df744bc79ec7

(reverted due to tests failing on non-linux/x86 targets, tests have since been
generalized and specialized... since Split DWARF isn't supported on non-elf
targets anyway and we have no way to run on "whatever elf target is available"
so they fail on MacOS without an explicit target triple)

This code was incorrectly emitting extra bytes into arbitrary parts of
the object file when it was meant to be hashing them to compute the DWO
ID.

Follow-up patch(es) will refactor this API somewhat to make such bugs
harder to introduce, hopefully.

Added: 
    

Modified: 
    llvm/lib/CodeGen/AsmPrinter/ByteStreamer.h
    llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
    llvm/test/DebugInfo/X86/convert-loclist.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/CodeGen/AsmPrinter/ByteStreamer.h b/llvm/lib/CodeGen/AsmPrinter/ByteStreamer.h
index 09f7496cd4ef..b60f68ca59b8 100644
--- a/llvm/lib/CodeGen/AsmPrinter/ByteStreamer.h
+++ b/llvm/lib/CodeGen/AsmPrinter/ByteStreamer.h
@@ -50,7 +50,7 @@ class APByteStreamer final : public ByteStreamer {
   }
   void EmitULEB128(uint64_t DWord, const Twine &Comment, unsigned PadTo) override {
     AP.OutStreamer->AddComment(Comment);
-    AP.EmitULEB128(DWord);
+    AP.EmitULEB128(DWord, nullptr, PadTo);
   }
 };
 

diff  --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 0923394ceb6e..447d3fa3e206 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -2241,7 +2241,7 @@ void DwarfDebug::emitDebugLocEntry(ByteStreamer &Streamer,
         uint64_t Offset =
             CU->ExprRefedBaseTypes[Op.getRawOperand(I)].Die->getOffset();
         assert(Offset < (1ULL << (ULEB128PadSize * 7)) && "Offset wont fit");
-        Asm->EmitULEB128(Offset, nullptr, ULEB128PadSize);
+        Streamer.EmitULEB128(Offset, "", ULEB128PadSize);
         // Make sure comments stay aligned.
         for (unsigned J = 0; J < ULEB128PadSize; ++J)
           if (Comment != End)

diff  --git a/llvm/test/DebugInfo/X86/convert-loclist.ll b/llvm/test/DebugInfo/X86/convert-loclist.ll
index a12ce5c766a0..2421ee1f5e03 100644
--- a/llvm/test/DebugInfo/X86/convert-loclist.ll
+++ b/llvm/test/DebugInfo/X86/convert-loclist.ll
@@ -1,7 +1,24 @@
 ; RUN: %llc_dwarf -filetype=obj < %s \
 ; RUN:   | llvm-dwarfdump -debug-info -debug-loclists - | FileCheck %s
 ; RUN: llc -mtriple x86_64-pc-linux -split-dwarf-file=foo.dwo -filetype=obj < %s \
-; RUN:   | llvm-dwarfdump -debug-info -debug-loclists - | FileCheck %s
+; RUN:   | llvm-dwarfdump -debug-info -debug-loclists - | FileCheck --check-prefix=SPLIT --check-prefix=CHECK %s
+; RUN: llc -mtriple x86_64-pc-linux -split-dwarf-file=foo.dwo -filetype=asm < %s \
+; RUN:   | FileCheck --check-prefix=ASM %s
+
+; A bit of a brittle test - this is testing the specific DWO_id. The
+; alternative would be to test two files with 
diff erent DW_OP_convert values &
+; ensuring the DWO IDs 
diff er when the DW_OP_convert parameter 
diff ers.
+
+; So if this test ends up being a brittle pain to maintain, updating the DWO ID
+; often - add another IR file with a 
diff erent DW_OP_convert that's otherwise
+; identical and demonstrate that they have 
diff erent DWO IDs.
+
+; SPLIT: 0x00000000: Compile Unit: {{.*}} DWO_id = 0xafd73565c68bc661
+
+; Regression testing a fairly quirky bug where instead of hashing (see above),
+; extra bytes would be emitted into the output assembly in no
+; particular/intentional section - so let's check they don't show up at all:
+; ASM-NOT: .asciz  "\200\200\200"
 
 ; CHECK: 0x{{0*}}[[TYPE:.*]]: DW_TAG_base_type
 ; CHECK-NEXT:                   DW_AT_name ("DW_ATE_unsigned_32")