Mips ELF: Mark object file as ABI compliant

When producing objects that are abi compliant we are 
marking neither the object file nor the assembly file
correctly and thus generate warnings. 

We need to set the EF_CPIC flag in the ELF header when
generating direct object.

Note that the warning is only generated when compiling without PIC.

When compiling with clang the warning will be suppressed by supplying:

 -Wa,-mno-shared -Wa,-call_nonpic

Also the following directive should also be added:

	.option	pic0

when compiling without PIC,  This eliminates the need for supplying:

  -mno-shared -call_nonpic

on the assembler command line.

Patch by Douglas Gilmore

llvm-svn: 184220

4 files changed, 41 insertions, 12 deletions

diff --git a/llvm/lib/Target/Mips/MCTargetDesc/MipsELFStreamer.cpp b/llvm/lib/Target/Mips/MCTargetDesc/MipsELFStreamer.cpp
index c33bc9ae303..cfcb877805a 100644
--- a/llvm/lib/Target/Mips/MCTargetDesc/MipsELFStreamer.cpp
+++ b/llvm/lib/Target/Mips/MCTargetDesc/MipsELFStreamer.cpp
@@ -36,6 +36,10 @@ namespace llvm {
     MCAssembler& MCA = getAssembler();
     unsigned EFlags = MCA.getELFHeaderEFlags();
 
+    // TODO: Need to add -mabicalls and -mno-abicalls flags.
+    // Currently we assume that -mabicalls is the default.
+    EFlags |= ELF::EF_MIPS_CPIC;
+
     if (Subtarget.inMips16Mode())
       EFlags |= ELF::EF_MIPS_ARCH_ASE_M16;
     else
diff --git a/llvm/lib/Target/Mips/MipsAsmPrinter.cpp b/llvm/lib/Target/Mips/MipsAsmPrinter.cpp
index 638001bb458..bab70afd398 100644
--- a/llvm/lib/Target/Mips/MipsAsmPrinter.cpp
+++ b/llvm/lib/Target/Mips/MipsAsmPrinter.cpp
@@ -557,6 +557,15 @@ printFCCOperand(const MachineInstr *MI, int opNum, raw_ostream &O,
 void MipsAsmPrinter::EmitStartOfAsmFile(Module &M) {
   // FIXME: Use SwitchSection.
 
+  // TODO: Need to add -mabicalls and -mno-abicalls flags.
+  // Currently we assume that -mabicalls is the default.
+  if (OutStreamer.hasRawTextSupport()) {
+    OutStreamer.EmitRawText(StringRef("\t.abicalls"));
+    Reloc::Model RM = Subtarget->getRelocationModel();
+    if (RM == Reloc::Static)
+      OutStreamer.EmitRawText(StringRef("\t.option\tpic0"));
+  }
+
   // Tell the assembler which ABI we are using
   if (OutStreamer.hasRawTextSupport())
     OutStreamer.EmitRawText("\t.section .mdebug." +
diff --git a/llvm/test/MC/Mips/abicalls.ll b/llvm/test/MC/Mips/abicalls.ll
new file mode 100644
index 00000000000..a93ae6d9c66
--- /dev/null
+++ b/llvm/test/MC/Mips/abicalls.ll
@@ -0,0 +1,13 @@
+; 
+; When the assembler is ready a .s file for it will
+; be created.
+
+; Note that EF_MIPS_CPIC is set by -mabicalls which is the default on Linux
+; TODO need to support -mno-abicalls
+
+; RUN: llc -filetype=asm -mtriple mipsel-unknown-linux -mcpu=mips32 -relocation-model=static %s -o - | FileCheck -check-prefix=CHECK-STATIC %s
+; RUN: llc -filetype=asm -mtriple mipsel-unknown-linux -mcpu=mips32 %s -o - | FileCheck -check-prefix=CHECK-PIC %s
+; CHECK-STATIC: .abicalls
+; CHECK-STATIC-NEXT: pic0
+; CHECK-PIC: .abicalls
+; CHECK-PIC-NOT: pic0
diff --git a/llvm/test/MC/Mips/elf_eflags.ll b/llvm/test/MC/Mips/elf_eflags.ll
index 6d16a42aca2..91217bce071 100644
--- a/llvm/test/MC/Mips/elf_eflags.ll
+++ b/llvm/test/MC/Mips/elf_eflags.ll
@@ -6,13 +6,16 @@
 
 ; EF_MIPS_NOREORDER (0x00000001) is always on by default currently
 ; EF_MIPS_PIC (0x00000002)
-; EF_MIPS_CPIC (0x00000004) - not tested yet
+; EF_MIPS_CPIC (0x00000004) - See note below
 ; EF_MIPS_ABI2 (0x00000020) - n32 not tested yet
 ; EF_MIPS_ARCH_32 (0x50000000)
 ; EF_MIPS_ARCH_64 (0x60000000)
 ; EF_MIPS_ARCH_32R2 (0x70000000)
 ; EF_MIPS_ARCH_64R2 (0x80000000)
 
+; Note that EF_MIPS_CPIC is set by -mabicalls which is the default on Linux
+; TODO need to support -mno-abicalls
+
 ; RUN: llc -filetype=obj -mtriple mipsel-unknown-linux -mcpu=mips32 -relocation-model=static %s -o - | llvm-readobj -h | FileCheck -check-prefix=CHECK-BE32 %s
 ; RUN: llc -filetype=obj -mtriple mipsel-unknown-linux -mcpu=mips32 %s -o - | llvm-readobj -h | FileCheck -check-prefix=CHECK-BE32_PIC %s
 ; RUN: llc -filetype=obj -mtriple mipsel-unknown-linux -mcpu=mips32r2 -relocation-model=static %s -o - | llvm-readobj -h | FileCheck -check-prefix=CHECK-BE32R2 %s
@@ -28,37 +31,37 @@
 ; RUN: llc -filetype=obj -mtriple mipsel-unknown-linux -mcpu=mips32r2 -mattr=+mips16 -relocation-model=pic %s -o - | llvm-readobj -h | FileCheck -check-prefix=CHECK-LE32R2-MIPS16 %s
  
 ; 32(R1) bit with NO_REORDER and static
-; CHECK-BE32: Flags [ (0x50001001)
+; CHECK-BE32: Flags [ (0x50001005)
 ;
 ; 32(R1) bit with NO_REORDER and PIC
-; CHECK-BE32_PIC: Flags [ (0x50001003)
+; CHECK-BE32_PIC: Flags [ (0x50001007)
 ;
 ; 32R2 bit with NO_REORDER and static
-; CHECK-BE32R2: Flags [ (0x70001001)
+; CHECK-BE32R2: Flags [ (0x70001005)
 ;
 ; 32R2 bit with NO_REORDER and PIC
-; CHECK-BE32R2_PIC: Flags [ (0x70001003)
+; CHECK-BE32R2_PIC: Flags [ (0x70001007)
 ;
 ; 32R2 bit MICROMIPS with NO_REORDER and static
-; CHECK-BE32R2-MICROMIPS: Flags [ (0x72001001)
+; CHECK-BE32R2-MICROMIPS: Flags [ (0x72001005)
 ;
 ; 32R2 bit MICROMIPS with NO_REORDER and PIC
-;CHECK-BE32R2-MICROMIPS_PIC: Flags [ (0x72001003)
+;CHECK-BE32R2-MICROMIPS_PIC: Flags [ (0x72001007)
 ;
 ; 64(R1) bit with NO_REORDER and static
-; CHECK-BE64: Flags [ (0x60000001)
+; CHECK-BE64: Flags [ (0x60000005)
 ;
 ; 64(R1) bit with NO_REORDER and PIC
-; CHECK-BE64_PIC: Flags [ (0x60000003)
+; CHECK-BE64_PIC: Flags [ (0x60000007)
 ;
 ; 64R2 bit with NO_REORDER and static
-; CHECK-BE64R2: Flags [ (0x80000001)
+; CHECK-BE64R2: Flags [ (0x80000005)
 ;
 ; 64R2 bit with NO_REORDER and PIC
-; CHECK-BE64R2_PIC: Flags [ (0x80000003)
+; CHECK-BE64R2_PIC: Flags [ (0x80000007)
 ;
 ; 32R2 bit MIPS16 with PIC
-; CHECK-LE32R2-MIPS16: Flags [ (0x74001002)
+; CHECK-LE32R2-MIPS16: Flags [ (0x74001006)
  
 define i32 @main() nounwind {
 entry: