[llvm] r234195 - ARM: do not relax Thumb1 -> Thumb2 if only Thumb1 is available.
Tim Northover
tnorthover at apple.com
Mon Apr 6 11:44:42 PDT 2015
Author: tnorthover
Date: Mon Apr 6 13:44:42 2015
New Revision: 234195
URL: http://llvm.org/viewvc/llvm-project?rev=234195&view=rev
Log:
ARM: do not relax Thumb1 -> Thumb2 if only Thumb1 is available.
After recognising that a certain narrow instruction might need a relocation to
be represented, we used to unconditionally relax it to a Thumb2 instruction to
permit this. Unfortunately, some CPUs (e.g. v6m) don't even have most Thumb2
instructions, so we end up emitting a completely invalid instruction.
Theoretically, ELF does have relocations for these situations; but they are
fairly unusable with such short ranges and the ABI document even says they're
documented "for completeness". So an error is probably better there too.
rdar://20391953
Added:
llvm/trunk/test/MC/ARM/thumb1-relax-adr.s
llvm/trunk/test/MC/ARM/thumb1-relax-bcc.s
llvm/trunk/test/MC/ARM/thumb1-relax-br.s
llvm/trunk/test/MC/ARM/thumb1-relax-ldrlit.s
Modified:
llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.h
llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp
llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMMachObjectWriter.cpp
Modified: llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp?rev=234195&r1=234194&r2=234195&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp (original)
+++ llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp Mon Apr 6 13:44:42 2015
@@ -153,18 +153,20 @@ void ARMAsmBackend::handleAssemblerFlag(
}
} // end anonymous namespace
-static unsigned getRelaxedOpcode(unsigned Op) {
+unsigned ARMAsmBackend::getRelaxedOpcode(unsigned Op) const {
+ bool HasThumb2 = STI->getFeatureBits() & ARM::FeatureThumb2;
+
switch (Op) {
default:
return Op;
case ARM::tBcc:
- return ARM::t2Bcc;
+ return HasThumb2 ? ARM::t2Bcc : Op;
case ARM::tLDRpci:
- return ARM::t2LDRpci;
+ return HasThumb2 ? ARM::t2LDRpci : Op;
case ARM::tADR:
- return ARM::t2ADR;
+ return HasThumb2 ? ARM::t2ADR : Op;
case ARM::tB:
- return ARM::t2B;
+ return HasThumb2 ? ARM::t2B : Op;
case ARM::tCBZ:
return ARM::tHINT;
case ARM::tCBNZ:
Modified: llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.h?rev=234195&r1=234194&r2=234195&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.h (original)
+++ llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.h Mon Apr 6 13:44:42 2015
@@ -47,6 +47,8 @@ public:
void applyFixup(const MCFixup &Fixup, char *Data, unsigned DataSize,
uint64_t Value, bool IsPCRel) const override;
+ unsigned getRelaxedOpcode(unsigned Op) const;
+
bool mayNeedRelaxation(const MCInst &Inst) const override;
bool fixupNeedsRelaxation(const MCFixup &Fixup, uint64_t Value,
Modified: llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp?rev=234195&r1=234194&r2=234195&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp (original)
+++ llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp Mon Apr 6 13:44:42 2015
@@ -81,7 +81,9 @@ unsigned ARMELFObjectWriter::GetRelocTyp
unsigned Type = 0;
if (IsPCRel) {
switch ((unsigned)Fixup.getKind()) {
- default: llvm_unreachable("Unimplemented");
+ default:
+ report_fatal_error("unsupported relocation on symbol");
+ return ELF::R_ARM_NONE;
case FK_Data_4:
switch (Modifier) {
default: llvm_unreachable("Unsupported Modifier");
@@ -147,7 +149,9 @@ unsigned ARMELFObjectWriter::GetRelocTyp
}
} else {
switch ((unsigned)Fixup.getKind()) {
- default: llvm_unreachable("invalid fixup kind!");
+ default:
+ report_fatal_error("unsupported relocation on symbol");
+ return ELF::R_ARM_NONE;
case FK_Data_1:
switch (Modifier) {
default: llvm_unreachable("unsupported Modifier");
Modified: llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMMachObjectWriter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMMachObjectWriter.cpp?rev=234195&r1=234194&r2=234195&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMMachObjectWriter.cpp (original)
+++ llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMMachObjectWriter.cpp Mon Apr 6 13:44:42 2015
@@ -88,6 +88,7 @@ static bool getARMFixupKindMachOInfo(uns
case ARM::fixup_arm_ldst_pcrel_12:
case ARM::fixup_arm_pcrel_10:
case ARM::fixup_arm_adr_pcrel_12:
+ case ARM::fixup_arm_thumb_br:
return false;
// Handle 24-bit branch kinds.
@@ -101,12 +102,6 @@ static bool getARMFixupKindMachOInfo(uns
Log2Size = llvm::Log2_32(4);
return true;
- // Handle Thumb branches.
- case ARM::fixup_arm_thumb_br:
- RelocType = unsigned(MachO::ARM_THUMB_RELOC_BR22);
- Log2Size = llvm::Log2_32(2);
- return true;
-
case ARM::fixup_t2_uncondbranch:
case ARM::fixup_arm_thumb_bl:
case ARM::fixup_arm_thumb_blx:
Added: llvm/trunk/test/MC/ARM/thumb1-relax-adr.s
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/ARM/thumb1-relax-adr.s?rev=234195&view=auto
==============================================================================
--- llvm/trunk/test/MC/ARM/thumb1-relax-adr.s (added)
+++ llvm/trunk/test/MC/ARM/thumb1-relax-adr.s Mon Apr 6 13:44:42 2015
@@ -0,0 +1,9 @@
+@ RUN: not llvm-mc -triple thumbv6m-none-macho -filetype=obj -o /dev/null %s 2>&1 | FileCheck --check-prefix=CHECK-ERROR %s
+@ RUN: not llvm-mc -triple thumbv7m-none-macho -filetype=obj -o /dev/null %s 2>&1 | FileCheck --check-prefix=CHECK-ERROR %s
+@ RUN: not llvm-mc -triple thumbv7m-none-eabi -filetype=obj -o /dev/null %s 2>&1 | FileCheck --check-prefix=CHECK-ERROR %s
+
+ .global func1
+_func1:
+ adr r0, _func2
+@ CHECK-ERROR: unsupported relocation on symbol
+
Added: llvm/trunk/test/MC/ARM/thumb1-relax-bcc.s
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/ARM/thumb1-relax-bcc.s?rev=234195&view=auto
==============================================================================
--- llvm/trunk/test/MC/ARM/thumb1-relax-bcc.s (added)
+++ llvm/trunk/test/MC/ARM/thumb1-relax-bcc.s Mon Apr 6 13:44:42 2015
@@ -0,0 +1,12 @@
+@ RUN: not llvm-mc -triple thumbv6m-none-macho -filetype=obj -o /dev/null %s 2>&1 | FileCheck --check-prefix=CHECK-ERROR %s
+@ RUN: not llvm-mc -triple thumbv7m-none-macho -filetype=obj -o /dev/null %s 2>&1 | FileCheck --check-prefix=CHECK-ERROR %s
+@ RUN: llvm-mc -triple thumbv7m-none-eabi -filetype=obj -o %t %s
+@ RUN: llvm-objdump -d -r -triple thumbv7m-none-eabi %t | FileCheck --check-prefix=CHECK-ELF %s
+
+ .global func1
+_func1:
+ bne _func2
+@ CHECK-ERROR: unsupported relocation on symbol
+
+@ CHECK-ELF: 7f f4 fe af bne.w #-4
+@ CHECK-ELF-NEXT: R_ARM_THM_JUMP24 _func2
Added: llvm/trunk/test/MC/ARM/thumb1-relax-br.s
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/ARM/thumb1-relax-br.s?rev=234195&view=auto
==============================================================================
--- llvm/trunk/test/MC/ARM/thumb1-relax-br.s (added)
+++ llvm/trunk/test/MC/ARM/thumb1-relax-br.s Mon Apr 6 13:44:42 2015
@@ -0,0 +1,19 @@
+@ RUN: not llvm-mc -triple thumbv6m-none-macho -filetype=obj -o /dev/null %s 2>&1 | FileCheck --check-prefix=CHECK-ERROR %s
+@ RUN: llvm-mc -triple thumbv7m-none-macho -filetype=obj -o %t %s
+@ RUN: llvm-objdump -d -r -triple thumbv7m-none-macho %t | FileCheck --check-prefix=CHECK-MACHO %s
+@ RUN: llvm-mc -triple thumbv7m-none-eabi -filetype=obj -o %t %s
+@ RUN: llvm-objdump -d -r -triple thumbv7m-none-eabi %t | FileCheck --check-prefix=CHECK-ELF %s
+
+ .global func1
+_func1:
+ @ There is no MachO relocation for Thumb1's unconditional branch, so
+ @ this is unrepresentable. FIXME: I think ELF could represent this.
+ b _func2
+
+@ CHECK-ERROR: unsupported relocation on symbol
+
+@ CHECK-MACHO: ff f7 fe bf b.w #-4
+@ CHECK-MACHO-NEXT: ARM_THUMB_RELOC_BR22
+
+@ CHECK-ELF: ff f7 fe bf b.w #-4
+@ CHECK-ELF-NEXT: R_ARM_THM_JUMP24 _func2
Added: llvm/trunk/test/MC/ARM/thumb1-relax-ldrlit.s
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/ARM/thumb1-relax-ldrlit.s?rev=234195&view=auto
==============================================================================
--- llvm/trunk/test/MC/ARM/thumb1-relax-ldrlit.s (added)
+++ llvm/trunk/test/MC/ARM/thumb1-relax-ldrlit.s Mon Apr 6 13:44:42 2015
@@ -0,0 +1,9 @@
+@ RUN: not llvm-mc -triple thumbv6m-none-macho -filetype=obj -o /dev/null %s 2>&1 | FileCheck --check-prefix=CHECK-ERROR %s
+@ RUN: not llvm-mc -triple thumbv7m-none-macho -filetype=obj -o /dev/null %s 2>&1 | FileCheck --check-prefix=CHECK-ERROR %s
+@ RUN: not llvm-mc -triple thumbv7m-none-eabi -filetype=obj -o /dev/null %s 2>&1 | FileCheck --check-prefix=CHECK-ERROR %s
+
+ .global func1
+_func1:
+ ldr r0, _func2
+@ CHECK-ERROR: unsupported relocation on symbol
+
More information about the llvm-commits
mailing list