From eb3e69e9ee59f747ace109c8170cadeb85b098fc Mon Sep 17 00:00:00 2001
From: Sam Parker <sam.parker@arm.com>
Date: Wed, 15 Mar 2017 10:21:23 +0000
Subject: [PATCH] [ARM] Fix for branch label disassembly for Thumb

Different MCInstrAnalysis classes for arm and thumb mode, each with
their own evaluateBranch implementation. I added a test case and
fixed the coff-relocations test to use '<label>:' rather than
'<label>' in the CHECK-LABEL entries, since the ones without the
colon would match branch targets. Might be worth noticing that
llvm-objdump does not lookup the relocation and thus assigns it a
target depending on the encoded immediate which #0, so it thinks it
branches to the next instruction.

Committed on behalf of Andre Vieira (avieira).

Differential Revision: https://reviews.llvm.org/D30943



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@297821 91177308-0d34-0410-b5e6-96231b3b80d8
---
 .../ARM/MCTargetDesc/ARMMCTargetDesc.cpp      | 88 ++++++++++-------
 test/MC/ARM/branch-disassemble.s              | 15 +++
 test/MC/ARM/coff-relocations.s                | 98 +++++++++----------
 3 files changed, 119 insertions(+), 82 deletions(-)
 create mode 100644 test/MC/ARM/branch-disassemble.s

diff --git a/lib/Target/ARM/MCTargetDesc/ARMMCTargetDesc.cpp b/lib/Target/ARM/MCTargetDesc/ARMMCTargetDesc.cpp
index 9e4d202321e..263671d69fa 100644
--- a/lib/Target/ARM/MCTargetDesc/ARMMCTargetDesc.cpp
+++ b/lib/Target/ARM/MCTargetDesc/ARMMCTargetDesc.cpp
@@ -257,24 +257,43 @@ public:
                       uint64_t Size, uint64_t &Target) const override {
     // We only handle PCRel branches for now.
     if (Info->get(Inst.getOpcode()).OpInfo[0].OperandType!=MCOI::OPERAND_PCREL)
-      return false;
-
-    int64_t Imm = Inst.getOperand(0).getImm();
-    // FIXME: This is not right for thumb.
-    Target = Addr+Imm+8; // In ARM mode the PC is always off by 8 bytes.
-    return true;
-  }
-};
-
-}
-
-static MCInstrAnalysis *createARMMCInstrAnalysis(const MCInstrInfo *Info) {
-  return new ARMMCInstrAnalysis(Info);
-}
-
-// Force static initialization.
-extern "C" void LLVMInitializeARMTargetMC() {
-  for (Target *T : {&getTheARMLETarget(), &getTheARMBETarget(),
+      return false;
+
+    int64_t Imm = Inst.getOperand(0).getImm();
+    Target = Addr+Imm+8; // In ARM mode the PC is always off by 8 bytes.
+    return true;
+  }
+};
+
+class ThumbMCInstrAnalysis : public ARMMCInstrAnalysis {
+public:
+  ThumbMCInstrAnalysis(const MCInstrInfo *Info) : ARMMCInstrAnalysis(Info) {}
+
+  bool evaluateBranch(const MCInst &Inst, uint64_t Addr,
+                      uint64_t Size, uint64_t &Target) const override {
+    // We only handle PCRel branches for now.
+    if (Info->get(Inst.getOpcode()).OpInfo[0].OperandType!=MCOI::OPERAND_PCREL)
+      return false;
+
+    int64_t Imm = Inst.getOperand(0).getImm();
+    Target = Addr+Imm+4; // In Thumb mode the PC is always off by 4 bytes.
+    return true;
+  }
+};
+
+}
+
+static MCInstrAnalysis *createARMMCInstrAnalysis(const MCInstrInfo *Info) {
+  return new ARMMCInstrAnalysis(Info);
+}
+
+static MCInstrAnalysis *createThumbMCInstrAnalysis(const MCInstrInfo *Info) {
+  return new ThumbMCInstrAnalysis(Info);
+}
+
+// Force static initialization.
+extern "C" void LLVMInitializeARMTargetMC() {
+  for (Target *T : {&getTheARMLETarget(), &getTheARMBETarget(),
                     &getTheThumbLETarget(), &getTheThumbBETarget()}) {
     // Register the MC asm info.
     RegisterMCAsmInfoFn X(*T, createARMMCAsmInfo);
@@ -286,15 +305,12 @@ extern "C" void LLVMInitializeARMTargetMC() {
     TargetRegistry::RegisterMCRegInfo(*T, createARMMCRegisterInfo);
 
     // Register the MC subtarget info.
-    TargetRegistry::RegisterMCSubtargetInfo(*T,
-                                            ARM_MC::createARMMCSubtargetInfo);
-
-    // Register the MC instruction analyzer.
-    TargetRegistry::RegisterMCInstrAnalysis(*T, createARMMCInstrAnalysis);
-
-    TargetRegistry::RegisterELFStreamer(*T, createELFStreamer);
-    TargetRegistry::RegisterCOFFStreamer(*T, createARMWinCOFFStreamer);
-    TargetRegistry::RegisterMachOStreamer(*T, createARMMachOStreamer);
+    TargetRegistry::RegisterMCSubtargetInfo(*T,
+                                            ARM_MC::createARMMCSubtargetInfo);
+
+    TargetRegistry::RegisterELFStreamer(*T, createELFStreamer);
+    TargetRegistry::RegisterCOFFStreamer(*T, createARMWinCOFFStreamer);
+    TargetRegistry::RegisterMachOStreamer(*T, createARMMachOStreamer);
 
     // Register the obj target streamer.
     TargetRegistry::RegisterObjectTargetStreamer(*T,
@@ -310,12 +326,18 @@ extern "C" void LLVMInitializeARMTargetMC() {
     TargetRegistry::RegisterMCInstPrinter(*T, createARMMCInstPrinter);
 
     // Register the MC relocation info.
-    TargetRegistry::RegisterMCRelocationInfo(*T, createARMMCRelocationInfo);
-  }
-
-  // Register the MC Code Emitter
-  for (Target *T : {&getTheARMLETarget(), &getTheThumbLETarget()})
-    TargetRegistry::RegisterMCCodeEmitter(*T, createARMLEMCCodeEmitter);
+    TargetRegistry::RegisterMCRelocationInfo(*T, createARMMCRelocationInfo);
+  }
+
+  // Register the MC instruction analyzer.
+  for (Target *T : {&getTheARMLETarget(), &getTheARMBETarget()})
+    TargetRegistry::RegisterMCInstrAnalysis(*T, createARMMCInstrAnalysis);
+  for (Target *T : {&getTheThumbLETarget(), &getTheThumbBETarget()})
+    TargetRegistry::RegisterMCInstrAnalysis(*T, createThumbMCInstrAnalysis);
+
+  // Register the MC Code Emitter
+  for (Target *T : {&getTheARMLETarget(), &getTheThumbLETarget()})
+    TargetRegistry::RegisterMCCodeEmitter(*T, createARMLEMCCodeEmitter);
   for (Target *T : {&getTheARMBETarget(), &getTheThumbBETarget()})
     TargetRegistry::RegisterMCCodeEmitter(*T, createARMBEMCCodeEmitter);
 
diff --git a/test/MC/ARM/branch-disassemble.s b/test/MC/ARM/branch-disassemble.s
new file mode 100644
index 00000000000..76cdea3292d
--- /dev/null
+++ b/test/MC/ARM/branch-disassemble.s
@@ -0,0 +1,15 @@
+@ RUN: llvm-mc -mcpu=cortex-a9 -triple armv7.arm-none-eabi -filetype obj -o - %s \
+@ RUN:   | llvm-objdump -mcpu=cortex-a9 -triple armv7.arm-none-eabi -d - \
+@ RUN:   | FileCheck %s -check-prefix CHECK-ARM
+
+@ RUN: llvm-mc -mcpu=cortex-m3 -triple thumbv7.arm-none-eabi -filetype obj -o - %s \
+@ RUN:   | llvm-objdump -mcpu=cortex-m3 -triple thumbv7.arm-none-eabi -d - \
+@ RUN:   | FileCheck %s -check-prefix CHECK-THUMB
+
+b.w .Lbranch
+@ CHECK-ARM: b #4 <$a.0+0xC>
+@ CHECK-THUMB: b.w #8 <$t.0+0xC>
+adds r0, r1, #42
+adds r1, r2, #42
+.Lbranch:
+movs r2, r3
diff --git a/test/MC/ARM/coff-relocations.s b/test/MC/ARM/coff-relocations.s
index fa2d407bb8f..d0c56b048cb 100644
--- a/test/MC/ARM/coff-relocations.s
+++ b/test/MC/ARM/coff-relocations.s
@@ -11,49 +11,49 @@
 	.global target
 
 	.thumb_func
-branch24t:
-	b target
-
-@ CHECK-ENCODING-LABEL: branch24t
-@ CHECK-ENCODING-NEXT: b.w #0
-
-	.thumb_func
-branch20t:
-	bcc target
-
-@ CHECK-ENCODING-LABEL: branch20t
-@ CHECK-ENCODING-NEXT: blo.w #0
-
-	.thumb_func
-blx23t:
-	bl target
-
-@ CHECK-ENCODING-LABEL: blx23t
-@ CHECK-ENCODING-NEXT: bl #0
-
-	.thumb_func
+branch24t:
+	b target
+
+@ CHECK-ENCODING-LABEL: branch24t:
+@ CHECK-ENCODING-NEXT: b.w #0
+
+	.thumb_func
+branch20t:
+	bcc target
+
+@ CHECK-ENCODING-LABEL: branch20t:
+@ CHECK-ENCODING-NEXT: blo.w #0
+
+	.thumb_func
+blx23t:
+	bl target
+
+@ CHECK-ENCODING-LABEL: blx23t:
+@ CHECK-ENCODING-NEXT: bl #0
+
+	.thumb_func
 mov32t:
 	movw r0, :lower16:target
-	movt r0, :upper16:target
-	blx r0
-
-@ CHECK-ENCODING-LABEL: mov32t
-@ CHECK-ENCODING-NEXT: movw r0, #0
-@ CHECK-ENCODING-NEXT: movt r0, #0
-@ CHECK-ENCODING-NEXT: blx r0
+	movt r0, :upper16:target
+	blx r0
+
+@ CHECK-ENCODING-LABEL: mov32t:
+@ CHECK-ENCODING-NEXT: movw r0, #0
+@ CHECK-ENCODING-NEXT: movt r0, #0
+@ CHECK-ENCODING-NEXT: blx r0
 
 	.thumb_func
 addr32:
 	ldr r0, .Laddr32
 	bx r0
 	trap
-.Laddr32:
-	.long target
-
-@ CHECK-ENCODING-LABEL: addr32
-@ CHECK-ENCODING-NEXT: ldr r0, [pc, #4]
-@ CHECK-ENCODING-NEXT: bx r0
-@ CHECK-ENCODING-NEXT: trap
+.Laddr32:
+	.long target
+
+@ CHECK-ENCODING-LABEL: addr32:
+@ CHECK-ENCODING-NEXT: ldr r0, [pc, #4]
+@ CHECK-ENCODING-NEXT: bx r0
+@ CHECK-ENCODING-NEXT: trap
 @ CHECK-ENCODING-NEXT: movs r0, r0
 @ CHECK-ENCODING-NEXT: movs r0, r0
 
@@ -62,13 +62,13 @@ addr32nb:
 	ldr r0, .Laddr32nb
 	bx r0
 	trap
-.Laddr32nb:
-	.long target(imgrel)
-
-@ CHECK-ENCODING-LABEL: addr32nb
-@ CHECK-ENCODING-NEXT: ldr.w r0, [pc, #4]
-@ CHECK-ENCODING-NEXT: bx r0
-@ CHECK-ENCODING-NEXT: trap
+.Laddr32nb:
+	.long target(imgrel)
+
+@ CHECK-ENCODING-LABEL: addr32nb:
+@ CHECK-ENCODING-NEXT: ldr.w r0, [pc, #4]
+@ CHECK-ENCODING-NEXT: bx r0
+@ CHECK-ENCODING-NEXT: trap
 @ CHECK-ENCODING-NEXT: movs r0, r0
 @ CHECK-ENCODING-NEXT: movs r0, r0
 
@@ -77,13 +77,13 @@ secrel:
 	ldr r0, .Lsecrel
 	bx r0
 	trap
-.Lsecrel:
-	.long target(secrel32)
-
-@ CHECK-ENCODING-LABEL: secrel
-@ CHECK-ENCODING-NEXT: ldr.w r0, [pc, #4]
-@ CHECK-ENCODING-NEXT: bx r0
-@ CHECK-ENCODING-NEXT: trap
+.Lsecrel:
+	.long target(secrel32)
+
+@ CHECK-ENCODING-LABEL: secrel:
+@ CHECK-ENCODING-NEXT: ldr.w r0, [pc, #4]
+@ CHECK-ENCODING-NEXT: bx r0
+@ CHECK-ENCODING-NEXT: trap
 @ CHECK-ENCODING-NEXT: movs r0, r0
 @ CHECK-ENCODING-NEXT: movs r0, r0
 
-- 
2.50.1