Ensure conditional BL instructions for ARM are given the fixup fixup_arm_condbranch.

Patch by Tim Northover!

llvm-svn: 153737

lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp

@@ -78,7 +78,8 @@ public:
 { "fixup_t2_condbranch",     0,            32,  MCFixupKindInfo::FKF_IsPCRel },
 { "fixup_t2_uncondbranch",   0,            32,  MCFixupKindInfo::FKF_IsPCRel },
 { "fixup_arm_thumb_br",      0,            16,  MCFixupKindInfo::FKF_IsPCRel },
-{ "fixup_arm_bl",            0,            24,  MCFixupKindInfo::FKF_IsPCRel },
+{ "fixup_arm_uncondbl",      0,            24,  MCFixupKindInfo::FKF_IsPCRel },
+{ "fixup_arm_condbl",        0,            24,  MCFixupKindInfo::FKF_IsPCRel },
 { "fixup_arm_blx",           0,            24,  MCFixupKindInfo::FKF_IsPCRel },
 { "fixup_arm_thumb_bl",      0,            32,  MCFixupKindInfo::FKF_IsPCRel },
 { "fixup_arm_thumb_blx",     0,            32,  MCFixupKindInfo::FKF_IsPCRel },
@@ -128,7 +129,8 @@ public:
     if (A && ((unsigned)Fixup.getKind() == ARM::fixup_arm_thumb_blx ||
               (unsigned)Fixup.getKind() == ARM::fixup_arm_thumb_bl ||
               (unsigned)Fixup.getKind() == ARM::fixup_arm_blx ||
-              (unsigned)Fixup.getKind() == ARM::fixup_arm_bl))
+              (unsigned)Fixup.getKind() == ARM::fixup_arm_uncondbl ||
+              (unsigned)Fixup.getKind() == ARM::fixup_arm_condbl))
       IsResolved = false;
   }
 
@@ -366,7 +368,8 @@ static unsigned adjustFixupValue(unsigned Kind, uint64_t Value) {
 
   case ARM::fixup_arm_condbranch:
   case ARM::fixup_arm_uncondbranch:
-  case ARM::fixup_arm_bl:
+  case ARM::fixup_arm_uncondbl:
+  case ARM::fixup_arm_condbl:
   case ARM::fixup_arm_blx:
     // These values don't encode the low two bits since they're always zero.
     // Offset by 8 just as above.
@@ -577,7 +580,8 @@ static unsigned getFixupKindNumBytes(unsigned Kind) {
   case ARM::fixup_arm_ldst_pcrel_12:
   case ARM::fixup_arm_pcrel_10:
   case ARM::fixup_arm_adr_pcrel_12:
-  case ARM::fixup_arm_bl:
+  case ARM::fixup_arm_uncondbl:
+  case ARM::fixup_arm_condbl:
   case ARM::fixup_arm_blx:
   case ARM::fixup_arm_condbranch:
   case ARM::fixup_arm_uncondbranch:

lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp

@@ -178,7 +178,7 @@ unsigned ARMELFObjectWriter::GetRelocTypeInner(const MCValue &Target,
         break;
       }
       break;
-    case ARM::fixup_arm_bl:
+    case ARM::fixup_arm_uncondbl:
     case ARM::fixup_arm_blx:
     case ARM::fixup_arm_uncondbranch:
       switch (Modifier) {
@@ -190,6 +190,7 @@ unsigned ARMELFObjectWriter::GetRelocTypeInner(const MCValue &Target,
         break;
       }
       break;
+    case ARM::fixup_arm_condbl:
     case ARM::fixup_arm_condbranch:
       Type = ELF::R_ARM_JUMP24;
       break;

lib/Target/ARM/MCTargetDesc/ARMFixupKinds.h

@@ -59,8 +59,21 @@ enum Fixups {
   // fixup_arm_thumb_br - 12-bit fixup for Thumb B instructions.
   fixup_arm_thumb_br,
 
-  // fixup_arm_bl - Fixup for ARM BL instructions.
+  // The following fixups handle the ARM BL instructions. These can be
-  fixup_arm_bl,
+  // conditionalised; however, the ARM ELF ABI requires a different relocation
+  // in that case: R_ARM_JUMP24 instead of R_ARM_CALL. The difference is that
+  // R_ARM_CALL is allowed to change the instruction to a BLX inline, which has
+  // no conditional version; R_ARM_JUMP24 would have to insert a veneer.
+  //
+  // MachO does not draw a distinction between the two cases, so it will treat
+  // fixup_arm_uncondbl and fixup_arm_condbl as identical fixups.
+
+  // fixup_arm_uncondbl - Fixup for unconditional ARM BL instructions.
+  fixup_arm_uncondbl,
+
+  // fixup_arm_condbl - Fixup for ARM BL instructions with nontrivial
+  // conditionalisation.
+  fixup_arm_condbl,
 
   // fixup_arm_blx - Fixup for ARM BLX instructions.
   fixup_arm_blx,

lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp

@@ -597,8 +597,12 @@ uint32_t ARMMCCodeEmitter::
 getARMBLTargetOpValue(const MCInst &MI, unsigned OpIdx,
                           SmallVectorImpl<MCFixup> &Fixups) const {
   const MCOperand MO = MI.getOperand(OpIdx);
-  if (MO.isExpr())
+  if (MO.isExpr()) {
-    return ::getBranchTargetOpValue(MI, OpIdx, ARM::fixup_arm_bl, Fixups);
+    if (HasConditionalBranch(MI))
+      return ::getBranchTargetOpValue(MI, OpIdx, 
+                                      ARM::fixup_arm_condbl, Fixups);
+    return ::getBranchTargetOpValue(MI, OpIdx, ARM::fixup_arm_uncondbl, Fixups);
+  }
 
   return MO.getImm() >> 2;
 }

lib/Target/ARM/MCTargetDesc/ARMMachObjectWriter.cpp

@@ -82,7 +82,8 @@ static bool getARMFixupKindMachOInfo(unsigned Kind, unsigned &RelocType,
   case ARM::fixup_arm_adr_pcrel_12:
   case ARM::fixup_arm_condbranch:
   case ARM::fixup_arm_uncondbranch:
-  case ARM::fixup_arm_bl:
+  case ARM::fixup_arm_uncondbl:
+  case ARM::fixup_arm_condbl:
   case ARM::fixup_arm_blx:
     RelocType = unsigned(macho::RIT_ARM_Branch24Bit);
     // Report as 'long', even though that is not quite accurate.

test/MC/ARM/arm_fixups.s

@@ -3,7 +3,7 @@
 
     bl _printf
 @ CHECK: bl _printf @ encoding: [A,A,A,0xeb]
-@ CHECK: @ fixup A - offset: 0, value: _printf, kind: fixup_arm_bl
+@ CHECK: @ fixup A - offset: 0, value: _printf, kind: fixup_arm_uncondbl
 
     mov r9, :lower16:(_foo)
     movw r9, :lower16:(_foo)

test/MC/ARM/basic-arm-instructions.s

@@ -382,13 +382,16 @@ Lforward:
 @------------------------------------------------------------------------------
 
         bl _bar
+        bleq _bar
         blx _bar
         blls #28634268
         blx	#32424576
         blx	#16212288
 
 @ CHECK: bl  _bar @ encoding: [A,A,A,0xeb]
-@ CHECK:   @   fixup A - offset: 0, value: _bar, kind: fixup_arm_bl
+@ CHECK:   @   fixup A - offset: 0, value: _bar, kind: fixup_arm_uncondbl
+@ CHECK: bleq  _bar @ encoding: [A,A,A,0x0b]
+@ CHECK:   @   fixup A - offset: 0, value: _bar, kind: fixup_arm_condbl
 @ CHECK: blx	_bar @ encoding: [A,A,A,0xfa]
            @   fixup A - offset: 0, value: _bar, kind: fixup_arm_blx
 @ CHECK: blls	#28634268               @ encoding: [0x27,0x3b,0x6d,0x9b]

test/MC/ARM/elf-reloc-condcall.s

@@ -0,0 +1,23 @@
+// RUN: llvm-mc -triple=armv7-linux-gnueabi -filetype=obj %s -o - | \
+// RUN:   elf-dump | FileCheck -check-prefix=OBJ %s
+
+        bleq some_label
+        bl some_label
+        blx some_label
+// OBJ: .rel.text
+
+// OBJ: 'r_offset', 0x00000000
+// OBJ-NEXT:  'r_sym', 0x000004
+// OBJ-NEXT: 'r_type', 0x1d
+
+// OBJ: 'r_offset', 0x00000004
+// OBJ-NEXT:  'r_sym', 0x000004
+// OBJ-NEXT: 'r_type', 0x1c
+
+// OBJ: 'r_offset', 0x00000008
+// OBJ-NEXT:  'r_sym', 0x000004
+// OBJ-NEXT: 'r_type', 0x1c
+
+// OBJ: .symtab
+// OBJ: Symbol 4
+// OBJ-NEXT: some_label