[mips] Work around inconsistency in llvm-mc's placement of fixup markers

Summary:
Add a second fixup table to MipsAsmBackend::getFixupKindInfo() to correctly
position llvm-mc's fixup placeholders for big-endian.

See PR19836 for full details of the issue. To summarize, the fixup placeholders
do not account for endianness properly and the implementations of
getFixupKindInfo() for each target are measuring MCFixupKindInfo.TargetOffset
from different ends of the instruction encoding to compensate.

Reviewers: jkolek, zoran.jovanovic, vmedic

Reviewed By: vmedic

Differential Revision: http://reviews.llvm.org/D3889

llvm-svn: 209514

5 files changed, 82 insertions, 13 deletions

diff --git a/llvm/lib/Target/Mips/MCTargetDesc/MipsAsmBackend.cpp b/llvm/lib/Target/Mips/MCTargetDesc/MipsAsmBackend.cpp
index 153974e470f..332f7ea7a26 100644
--- a/llvm/lib/Target/Mips/MCTargetDesc/MipsAsmBackend.cpp
+++ b/llvm/lib/Target/Mips/MCTargetDesc/MipsAsmBackend.cpp
@@ -189,7 +189,7 @@ void MipsAsmBackend::applyFixup(const MCFixup &Fixup, char *Data,
 
 const MCFixupKindInfo &MipsAsmBackend::
 getFixupKindInfo(MCFixupKind Kind) const {
-  const static MCFixupKindInfo Infos[Mips::NumTargetFixupKinds] = {
+  const static MCFixupKindInfo LittleEndianInfos[Mips::NumTargetFixupKinds] = {
     // This table *must* be in same the order of fixup_* kinds in
     // MipsFixupKinds.h.
     //
@@ -246,12 +246,72 @@ getFixupKindInfo(MCFixupKind Kind) const {
     { "fixup_MICROMIPS_TLS_TPREL_LO16",  0,     16,   0 }
   };
 
+  const static MCFixupKindInfo BigEndianInfos[Mips::NumTargetFixupKinds] = {
+    // This table *must* be in same the order of fixup_* kinds in
+    // MipsFixupKinds.h.
+    //
+    // name                    offset  bits  flags
+    { "fixup_Mips_16",          16,     16,   0 },
+    { "fixup_Mips_32",           0,     32,   0 },
+    { "fixup_Mips_REL32",        0,     32,   0 },
+    { "fixup_Mips_26",           6,     26,   0 },
+    { "fixup_Mips_HI16",        16,     16,   0 },
+    { "fixup_Mips_LO16",        16,     16,   0 },
+    { "fixup_Mips_GPREL16",     16,     16,   0 },
+    { "fixup_Mips_LITERAL",     16,     16,   0 },
+    { "fixup_Mips_GOT_Global",  16,     16,   0 },
+    { "fixup_Mips_GOT_Local",   16,     16,   0 },
+    { "fixup_Mips_PC16",        16,     16,  MCFixupKindInfo::FKF_IsPCRel },
+    { "fixup_Mips_CALL16",      16,     16,   0 },
+    { "fixup_Mips_GPREL32",      0,     32,   0 },
+    { "fixup_Mips_SHIFT5",      21,      5,   0 },
+    { "fixup_Mips_SHIFT6",      21,      5,   0 },
+    { "fixup_Mips_64",           0,     64,   0 },
+    { "fixup_Mips_TLSGD",       16,     16,   0 },
+    { "fixup_Mips_GOTTPREL",    16,     16,   0 },
+    { "fixup_Mips_TPREL_HI",    16,     16,   0 },
+    { "fixup_Mips_TPREL_LO",    16,     16,   0 },
+    { "fixup_Mips_TLSLDM",      16,     16,   0 },
+    { "fixup_Mips_DTPREL_HI",   16,     16,   0 },
+    { "fixup_Mips_DTPREL_LO",   16,     16,   0 },
+    { "fixup_Mips_Branch_PCRel",16,     16,  MCFixupKindInfo::FKF_IsPCRel },
+    { "fixup_Mips_GPOFF_HI",    16,     16,   0 },
+    { "fixup_Mips_GPOFF_LO",    16,     16,   0 },
+    { "fixup_Mips_GOT_PAGE",    16,     16,   0 },
+    { "fixup_Mips_GOT_OFST",    16,     16,   0 },
+    { "fixup_Mips_GOT_DISP",    16,     16,   0 },
+    { "fixup_Mips_HIGHER",      16,     16,   0 },
+    { "fixup_Mips_HIGHEST",     16,     16,   0 },
+    { "fixup_Mips_GOT_HI16",    16,     16,   0 },
+    { "fixup_Mips_GOT_LO16",    16,     16,   0 },
+    { "fixup_Mips_CALL_HI16",   16,     16,   0 },
+    { "fixup_Mips_CALL_LO16",   16,     16,   0 },
+    { "fixup_MICROMIPS_26_S1",   6,     26,   0 },
+    { "fixup_MICROMIPS_HI16",   16,     16,   0 },
+    { "fixup_MICROMIPS_LO16",   16,     16,   0 },
+    { "fixup_MICROMIPS_GOT16",  16,     16,   0 },
+    { "fixup_MICROMIPS_PC16_S1",16,     16,   MCFixupKindInfo::FKF_IsPCRel },
+    { "fixup_MICROMIPS_CALL16", 16,     16,   0 },
+    { "fixup_MICROMIPS_GOT_DISP",        16,     16,   0 },
+    { "fixup_MICROMIPS_GOT_PAGE",        16,     16,   0 },
+    { "fixup_MICROMIPS_GOT_OFST",        16,     16,   0 },
+    { "fixup_MICROMIPS_TLS_GD",          16,     16,   0 },
+    { "fixup_MICROMIPS_TLS_LDM",         16,     16,   0 },
+    { "fixup_MICROMIPS_TLS_DTPREL_HI16", 16,     16,   0 },
+    { "fixup_MICROMIPS_TLS_DTPREL_LO16", 16,     16,   0 },
+    { "fixup_MICROMIPS_TLS_TPREL_HI16",  16,     16,   0 },
+    { "fixup_MICROMIPS_TLS_TPREL_LO16",  16,     16,   0 }
+  };
+
   if (Kind < FirstTargetFixupKind)
     return MCAsmBackend::getFixupKindInfo(Kind);
 
   assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() &&
           "Invalid kind!");
-  return Infos[Kind - FirstTargetFixupKind];
+
+  if (IsLittle)
+    return LittleEndianInfos[Kind - FirstTargetFixupKind];
+  return BigEndianInfos[Kind - FirstTargetFixupKind];
 }
 
 /// WriteNopData - Write an (optimal) nop sequence of Count bytes
diff --git a/llvm/test/MC/Mips/llvm-mc-fixup-endianness.s b/llvm/test/MC/Mips/llvm-mc-fixup-endianness.s
new file mode 100644
index 00000000000..bc6a5d96632
--- /dev/null
+++ b/llvm/test/MC/Mips/llvm-mc-fixup-endianness.s
@@ -0,0 +1,6 @@
+# RUN: llvm-mc -show-encoding -mcpu=mips32 -triple mips-unknown-unknown %s | FileCheck -check-prefix=BE %s
+# RUN: llvm-mc -show-encoding -mcpu=mips32 -triple mipsel-unknown-unknown %s | FileCheck -check-prefix=LE %s
+#
+        .text
+        b foo # BE: b foo # encoding: [0x10,0x00,A,A]
+              # LE: b foo # encoding: [A,A,0x00,0x10]
diff --git a/llvm/test/MC/Mips/mips_directives.s b/llvm/test/MC/Mips/mips_directives.s
index 6780dd0b3ca..1a7d61f3ad4 100644
--- a/llvm/test/MC/Mips/mips_directives.s
+++ b/llvm/test/MC/Mips/mips_directives.s
@@ -51,7 +51,7 @@ $BB0_4:
     .set  $tmp7, $BB0_4-$BB0_2
     .set f6,$f6
 # CHECK:    abs.s   $f6, $f7           # encoding: [0x46,0x00,0x39,0x85]
-# CHECK:    lui     $1, %hi($tmp7)     # encoding: [0x3c'A',0x01'A',0x00,0x00]
+# CHECK:    lui     $1, %hi($tmp7)     # encoding: [0x3c,0x01,A,A]
 # CHECK:                               #   fixup A - offset: 0, value: ($tmp7)@ABS_HI, kind: fixup_Mips_HI16
     abs.s  f6,FPU_MASK
     lui $1, %hi($tmp7)
diff --git a/llvm/test/MC/Mips/mips_gprel16.s b/llvm/test/MC/Mips/mips_gprel16.s
index 716c75ec88d..9dd3fa3281c 100644
--- a/llvm/test/MC/Mips/mips_gprel16.s
+++ b/llvm/test/MC/Mips/mips_gprel16.s
@@ -6,6 +6,9 @@
 // RUN: llvm-mc -mcpu=mips32r2 -triple=mipsel-pc-linux -filetype=obj -relocation-model=static %s -o - \
 // RUN: | llvm-objdump -disassemble -mattr +mips32r2 - \
 // RUN: | FileCheck %s
+// RUN: llvm-mc -mcpu=mips32r2 -triple=mips-pc-linux -filetype=obj -relocation-model=static %s -o - \
+// RUN: | llvm-objdump -disassemble -mattr +mips32r2 - \
+// RUN: | FileCheck %s
 
 	.text
 	.abicalls
diff --git a/llvm/test/MC/Mips/msa/test_cbranch.s b/llvm/test/MC/Mips/msa/test_cbranch.s
index 37b88725602..aa6779b1b46 100644
--- a/llvm/test/MC/Mips/msa/test_cbranch.s
+++ b/llvm/test/MC/Mips/msa/test_cbranch.s
@@ -7,22 +7,22 @@
 #CHECK:      bnz.w        $w2, 128      # encoding: [0x47,0xc2,0x00,0x20]
 #CHECK:      nop                        # encoding: [0x00,0x00,0x00,0x00]
 #CHECK:      bnz.d        $w3, -128     # encoding: [0x47,0xe3,0xff,0xe0]
-#CHECK:      bnz.b        $w0, SYMBOL0  # encoding: [0x47'A',0x80'A',0x00,0x00]
+#CHECK:      bnz.b        $w0, SYMBOL0  # encoding: [0x47,0x80,A,A]
                                         #   fixup A - offset: 0, value: SYMBOL0, kind: fixup_Mips_PC16
 #CHECK:      nop                        # encoding: [0x00,0x00,0x00,0x00]
-#CHECK:      bnz.h        $w1, SYMBOL1  # encoding: [0x47'A',0xa1'A',0x00,0x00]
+#CHECK:      bnz.h        $w1, SYMBOL1  # encoding: [0x47,0xa1,A,A]
                                         #   fixup A - offset: 0, value: SYMBOL1, kind: fixup_Mips_PC16
 #CHECK:      nop                        # encoding: [0x00,0x00,0x00,0x00]
-#CHECK:      bnz.w        $w2, SYMBOL2  # encoding: [0x47'A',0xc2'A',0x00,0x00]
+#CHECK:      bnz.w        $w2, SYMBOL2  # encoding: [0x47,0xc2,A,A]
                                         #   fixup A - offset: 0, value: SYMBOL2, kind: fixup_Mips_PC16
 #CHECK:      nop                        # encoding: [0x00,0x00,0x00,0x00]
-#CHECK:      bnz.d        $w3, SYMBOL3  # encoding: [0x47'A',0xe3'A',0x00,0x00]
+#CHECK:      bnz.d        $w3, SYMBOL3  # encoding: [0x47,0xe3,A,A]
                                         #   fixup A - offset: 0, value: SYMBOL3, kind: fixup_Mips_PC16
 #CHECK:      nop                        # encoding: [0x00,0x00,0x00,0x00]
 
 #CHECK:      bnz.v        $w0, 4        # encoding: [0x45,0xe0,0x00,0x01]
 #CHECK:      nop                        # encoding: [0x00,0x00,0x00,0x00]
-#CHECK:      bnz.v        $w0, SYMBOL0  # encoding: [0x45'A',0xe0'A',0x00,0x00]
+#CHECK:      bnz.v        $w0, SYMBOL0  # encoding: [0x45,0xe0,A,A]
                                         #   fixup A - offset: 0, value: SYMBOL0, kind: fixup_Mips_PC16
 #CHECK:      nop                        # encoding: [0x00,0x00,0x00,0x00]
 
@@ -34,22 +34,22 @@
 #CHECK:      nop                        # encoding: [0x00,0x00,0x00,0x00]
 #CHECK:      bz.d         $w3, -1024    # encoding: [0x47,0x63,0xff,0x00]
 #CHECK:      nop                        # encoding: [0x00,0x00,0x00,0x00]
-#CHECK:      bz.b         $w0, SYMBOL0  # encoding: [0x47'A',A,0x00,0x00]
+#CHECK:      bz.b         $w0, SYMBOL0  # encoding: [0x47,0x00,A,A]
                                         #   fixup A - offset: 0, value: SYMBOL0, kind: fixup_Mips_PC16
 #CHECK:      nop                        # encoding: [0x00,0x00,0x00,0x00]
-#CHECK:      bz.h         $w1, SYMBOL1  # encoding: [0x47'A',0x21'A',0x00,0x00]
+#CHECK:      bz.h         $w1, SYMBOL1  # encoding: [0x47,0x21,A,A]
                                         #   fixup A - offset: 0, value: SYMBOL1, kind: fixup_Mips_PC16
 #CHECK:      nop                        # encoding: [0x00,0x00,0x00,0x00]
-#CHECK:      bz.w         $w2, SYMBOL2  # encoding: [0x47'A',0x42'A',0x00,0x00]
+#CHECK:      bz.w         $w2, SYMBOL2  # encoding: [0x47,0x42,A,A]
                                         #   fixup A - offset: 0, value: SYMBOL2, kind: fixup_Mips_PC16
 #CHECK:      nop                        # encoding: [0x00,0x00,0x00,0x00]
-#CHECK:      bz.d         $w3, SYMBOL3  # encoding: [0x47'A',0x63'A',0x00,0x00]
+#CHECK:      bz.d         $w3, SYMBOL3  # encoding: [0x47,0x63,A,A]
                                         #   fixup A - offset: 0, value: SYMBOL3, kind: fixup_Mips_PC16
 #CHECK:      nop                        # encoding: [0x00,0x00,0x00,0x00]
 
 #CHECK:      bz.v        $w0, 4        # encoding: [0x45,0x60,0x00,0x01]
 #CHECK:      nop                       # encoding: [0x00,0x00,0x00,0x00]
-#CHECK:      bz.v        $w0, SYMBOL0  # encoding: [0x45'A',0x60'A',0x00,0x00]
+#CHECK:      bz.v        $w0, SYMBOL0  # encoding: [0x45,0x60,A,A]
                                        #   fixup A - offset: 0, value: SYMBOL0, kind: fixup_Mips_PC16
 #CHECK:      nop                       # encoding: [0x00,0x00,0x00,0x00]