From 5604ab9da4dadbfec85c650da27f841932c9cde8 Mon Sep 17 00:00:00 2001
From: Oliver Stannard <oliver.stannard@arm.com>
Date: Thu, 1 May 2014 08:46:02 +0000
Subject: [PATCH] Record the DWARF version in MCContext

Record the DWARF version in MCContext, and use it when
emitting the dwarf version into the debug info.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207739 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/MC/MCContext.h |  6 ++++++
 lib/MC/MCDwarf.cpp          |  4 ++--
 test/MC/ELF/gen-dwarf.s     | 14 +++++++++++---
 tools/llvm-mc/llvm-mc.cpp   |  9 +++++++++
 4 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/include/llvm/MC/MCContext.h b/include/llvm/MC/MCContext.h
index d2397154b47..7557e7629bb 100644
--- a/include/llvm/MC/MCContext.h
+++ b/include/llvm/MC/MCContext.h
@@ -147,6 +147,9 @@ namespace llvm {
     /// non-empty.
     StringRef DwarfDebugProducer;
 
+    /// The maximum version of dwarf that we should emit.
+    uint16_t DwarfVersion;
+
     /// Honor temporary labels, this is useful for debugging semantic
     /// differences between temporary and non-temporary labels (primarily on
     /// Darwin).
@@ -396,6 +399,9 @@ namespace llvm {
     void setDwarfDebugProducer(StringRef S) { DwarfDebugProducer = S; }
     StringRef getDwarfDebugProducer() { return DwarfDebugProducer; }
 
+    void setDwarfVersion(uint16_t v) { DwarfVersion = v; }
+    uint16_t getDwarfVersion() const { return DwarfVersion; }
+
     /// @}
 
     char *getSecureLogFile() { return SecureLogFile; }
diff --git a/lib/MC/MCDwarf.cpp b/lib/MC/MCDwarf.cpp
index 8c9f15af18f..7481e45c596 100644
--- a/lib/MC/MCDwarf.cpp
+++ b/lib/MC/MCDwarf.cpp
@@ -645,8 +645,8 @@ static void EmitGenDwarfInfo(MCStreamer *MCOS,
   const MCExpr *Length = MakeStartMinusEndExpr(*MCOS, *InfoStart, *InfoEnd, 4);
   MCOS->EmitAbsValue(Length, 4);
 
-  // The 2 byte DWARF version, which is 2.
-  MCOS->EmitIntValue(2, 2);
+  // The 2 byte DWARF version.
+  MCOS->EmitIntValue(context.getDwarfVersion(), 2);
 
   // The 4 byte offset to the debug abbrevs from the start of the .debug_abbrev,
   // it is at the start of that section so this is zero.
diff --git a/test/MC/ELF/gen-dwarf.s b/test/MC/ELF/gen-dwarf.s
index 946119bb248..7f0c0594ce9 100644
--- a/test/MC/ELF/gen-dwarf.s
+++ b/test/MC/ELF/gen-dwarf.s
@@ -1,5 +1,9 @@
-// RUN: llvm-mc -g -triple  i686-pc-linux-gnu %s -filetype=obj -o - | llvm-readobj -r | FileCheck %s
-// RUN: llvm-mc -g -triple  i686-pc-linux-gnu %s -filetype=asm -o - | FileCheck --check-prefix=ASM %s
+// RUN: llvm-mc -g -dwarf-version 2 -triple  i686-pc-linux-gnu %s -filetype=obj -o - | llvm-readobj -r | FileCheck %s
+// RUN: not llvm-mc -g -dwarf-version 1  -triple  i686-pc-linux-gnu %s -filetype=asm -o - 2>&1 | FileCheck --check-prefix=DWARF1 %s
+// RUN: llvm-mc -g -dwarf-version 2 -triple  i686-pc-linux-gnu %s -filetype=asm -o - | FileCheck --check-prefix=ASM --check-prefix=DWARF2 %s
+// RUN: llvm-mc -g -dwarf-version 3 -triple  i686-pc-linux-gnu %s -filetype=asm -o - | FileCheck --check-prefix=ASM --check-prefix=DWARF3 %s
+// RUN: llvm-mc -g -triple  i686-pc-linux-gnu %s -filetype=asm -o - | FileCheck --check-prefix=ASM --check-prefix=DWARF4 %s
+// RUN: not llvm-mc -g -dwarf-version 5  -triple  i686-pc-linux-gnu %s -filetype=asm -o - 2>&1 | FileCheck --check-prefix=DWARF5 %s
 
 
 // Test that on ELF:
@@ -35,7 +39,9 @@ foo:
 // Second instance of the section has the CU
 // ASM: .section .debug_info
 // Dwarf version
-// ASM: .short 2
+// DWARF2: .short 2
+// DWARF3: .short 3
+// DWARF4: .short 4
 // ASM-NEXT: .long [[ABBREV_LABEL]]
 // First .byte 1 is the abbreviation number for the compile_unit abbrev
 // ASM: .byte 1
@@ -44,3 +50,5 @@ foo:
 // ASM: .section .debug_line
 // ASM-NEXT: [[LINE_LABEL]]
 
+// DWARF1: Dwarf version 1 is not supported.
+// DWARF5: Dwarf version 5 is not supported.
diff --git a/tools/llvm-mc/llvm-mc.cpp b/tools/llvm-mc/llvm-mc.cpp
index dbe012b4d4a..516f6234f29 100644
--- a/tools/llvm-mc/llvm-mc.cpp
+++ b/tools/llvm-mc/llvm-mc.cpp
@@ -154,6 +154,9 @@ static cl::opt<bool>
 GenDwarfForAssembly("g", cl::desc("Generate dwarf debugging info for assembly "
                                   "source files"));
 
+static cl::opt<int>
+DwarfVersion("dwarf-version", cl::desc("Dwarf version"), cl::init(4));
+
 static cl::opt<std::string>
 DebugCompilationDir("fdebug-compilation-dir",
                     cl::desc("Specifies the debug info's compilation dir"));
@@ -406,6 +409,12 @@ int main(int argc, char **argv) {
     Ctx.setAllowTemporaryLabels(false);
 
   Ctx.setGenDwarfForAssembly(GenDwarfForAssembly);
+  if (DwarfVersion < 2 || DwarfVersion > 4) {
+    errs() << ProgName << ": Dwarf version " << DwarfVersion
+           << " is not supported." << '\n';
+    return 1;
+  }
+  Ctx.setDwarfVersion(DwarfVersion);
   if (!DwarfDebugFlags.empty())
     Ctx.setDwarfDebugFlags(StringRef(DwarfDebugFlags));
   if (!DwarfDebugProducer.empty())
-- 
2.34.1