atrosinenko created this revision.
atrosinenko added reviewers: echristo, rjmccall, krisb, mskvortsov, pftbest.
Herald added a subscriber: hiraditya.
Herald added projects: clang, LLVM.
When writing a unit test on replacing standard epilogue sequences with `BR
__mspabi_func_epilog_<N>`, by manually asm-clobbering `rN` - `r10` for N =
4..10, everything worked well except for seeming inability to clobber r4.
The problem was that MSP430 code generator of LLVM used an obsolete name FP for
that register. Things were worse because when `llc` read an unknown register
name, it silently ignored it.
Example: take the following source:
name=test-regs.c
void f(void)
{
asm volatile ("" : : : "r0");
asm volatile ("" : : : "r1");
asm volatile ("" : : : "r2");
asm volatile ("" : : : "r3");
asm volatile ("" : : : "r4");
asm volatile ("" : : : "r5");
}
void g(void)
{
asm volatile ("" : : : "pc");
asm volatile ("" : : : "sp");
asm volatile ("" : : : "sr");
asm volatile ("" : : : "cg");
asm volatile ("" : : : "fp");
asm volatile ("" : : : "r5");
}
and execute:
$ $sysroot/bin/msp430-elf-gcc --version
msp430-elf-gcc (Mitto Systems Limited - msp430-gcc 8.3.1.25) 8.3.1
Copyright (C) 2018 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
$ $sysroot/bin/msp430-elf-gcc -c test-regs.c
test-regs.c: In function 'g':
test-regs.c:14:3: error: unknown register name 'pc' in 'asm'
asm volatile ("" : : : "pc");
^~~
test-regs.c:15:3: error: unknown register name 'sp' in 'asm'
asm volatile ("" : : : "sp");
^~~
test-regs.c:16:3: error: unknown register name 'sr' in 'asm'
asm volatile ("" : : : "sr");
^~~
test-regs.c:17:3: error: unknown register name 'cg' in 'asm'
asm volatile ("" : : : "cg");
^~~
test-regs.c:18:3: error: unknown register name 'fp' in 'asm'
asm volatile ("" : : : "fp");
^~~
$ clang --version
clang version 10.0.0-4ubuntu1
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin
$ clang -target msp430 -c test-regs.c
test-regs.c:14:26: error: unknown register name 'pc' in asm
asm volatile ("" : : : "pc");
^
test-regs.c:15:26: error: unknown register name 'sp' in asm
asm volatile ("" : : : "sp");
^
test-regs.c:16:26: error: unknown register name 'sr' in asm
asm volatile ("" : : : "sr");
^
test-regs.c:17:26: error: unknown register name 'cg' in asm
asm volatile ("" : : : "cg");
^
test-regs.c:18:26: error: unknown register name 'fp' in asm
asm volatile ("" : : : "fp");
^
5 errors generated.
No differences at all. Now, let's drop `g()` function, to make it valid source.
$ clang -target msp430 test-regs.c -S -emit-llvm -o-
...
; Function Attrs: noinline nounwind optnone
define dso_local void @f() #0 {
call void asm sideeffect "", "~{r0}"() #1, !srcloc !2
call void asm sideeffect "", "~{r1}"() #1, !srcloc !3
call void asm sideeffect "", "~{r2}"() #1, !srcloc !4
call void asm sideeffect "", "~{r3}"() #1, !srcloc !5
call void asm sideeffect "", "~{r4}"() #1, !srcloc !6
call void asm sideeffect "", "~{r5}"() #1, !srcloc !7
ret void
}
...
Everything looks good, again.
$ clang -target msp430 test-regs.c -S -mllvm -stop-after=finalize-isel -o-
...
body: |
bb.0 (%ir-block.0):
INLINEASM &"", 1, !2
INLINEASM &"", 1, !3
INLINEASM &"", 1, !4
INLINEASM &"", 1, !5
INLINEASM &"", 1, !6
INLINEASM &"", 1, 12, implicit-def early-clobber $r5, !7
RET
That is, I cannot use `fp` register name from the C code because Clang does not
accept it (exactly like GCC). But the accepted name `r4` is not recognised by
`llc` (it can be used in listings passed to `llvm-mc` and even `fp` is replace
to `r4` by `llvm-mc`). So I can specify any of `fp` or `r4` for the string
literal of `asm(...)` but nothing in the clobber list.
This patch replaces `MSP430::FP` with `MSP430::R4` in the backend code (even
[MSP430 EABI](doesn't mention FP as a register name)). The R0 - R3
<https://reviews.llvm.org/source/clang/> registers, on the other hand, are left
as is in the backend code (after all, they have some special meaning on the ISA
level). It is just ensured clang is renaming them as expected by the downstream
tools. There is probably not much sense in **marking them clobbered** but
rename them //just in case// for use at potentially different contexts.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D82184
Files:
clang/lib/Basic/Targets/MSP430.h
clang/test/CodeGen/msp430-register-names.c
llvm/lib/Target/MSP430/AsmParser/MSP430AsmParser.cpp
llvm/lib/Target/MSP430/Disassembler/MSP430Disassembler.cpp
llvm/lib/Target/MSP430/MSP430FrameLowering.cpp
llvm/lib/Target/MSP430/MSP430ISelLowering.cpp
llvm/lib/Target/MSP430/MSP430RegisterInfo.cpp
llvm/lib/Target/MSP430/MSP430RegisterInfo.td
llvm/test/CodeGen/MSP430/asm-clobbers.ll
llvm/test/CodeGen/MSP430/inline-asm-register-names.ll
Index: llvm/test/CodeGen/MSP430/inline-asm-register-names.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/MSP430/inline-asm-register-names.ll
@@ -0,0 +1,59 @@
+; RUN: llc < %s | FileCheck %s
+target datalayout = "e-p:16:8:8-i8:8:8-i16:8:8-i32:8:8"
+target triple = "msp430-generic-generic"
+
+; Test that correct register names are accepted *inside* inline asm listings.
+; Tested with PUSH instruction since it does not support memory operands.
+
+define void @accepted_rN() nounwind {
+; CHECK-LABEL: accepted_rN
+ call void asm sideeffect "push r0", ""() nounwind
+; CHECK: push r0
+ call void asm sideeffect "push r1", ""() nounwind
+; CHECK: push r1
+ call void asm sideeffect "push r2", ""() nounwind
+; CHECK: push r2
+ call void asm sideeffect "push r3", ""() nounwind
+; CHECK: push r3
+ call void asm sideeffect "push r4", ""() nounwind
+; CHECK: push r4
+ call void asm sideeffect "push r5", ""() nounwind
+; CHECK: push r5
+ call void asm sideeffect "push r6", ""() nounwind
+; CHECK: push r6
+ call void asm sideeffect "push r7", ""() nounwind
+; CHECK: push r7
+ call void asm sideeffect "push r8", ""() nounwind
+; CHECK: push r8
+ call void asm sideeffect "push r9", ""() nounwind
+; CHECK: push r9
+ call void asm sideeffect "push r10", ""() nounwind
+; CHECK: push r10
+ call void asm sideeffect "push r11", ""() nounwind
+; CHECK: push r11
+ call void asm sideeffect "push r12", ""() nounwind
+; CHECK: push r12
+ call void asm sideeffect "push r13", ""() nounwind
+; CHECK: push r13
+ call void asm sideeffect "push r14", ""() nounwind
+; CHECK: push r14
+ call void asm sideeffect "push r15", ""() nounwind
+; CHECK: push r15
+ ret void
+}
+
+define void @accepted_reg_aliases() nounwind {
+; CHECK-LABEL: accepted_reg_aliases
+; Ensure register aliases are renamed as expected
+call void asm sideeffect "push pc", ""() nounwind
+; CHECK: push r0
+call void asm sideeffect "push sp", ""() nounwind
+; CHECK: push r1
+call void asm sideeffect "push sr", ""() nounwind
+; CHECK: push r2
+call void asm sideeffect "push cg", ""() nounwind
+; CHECK: push r3
+call void asm sideeffect "push fp", ""() nounwind
+; CHECK: push r4
+ ret void
+}
Index: llvm/test/CodeGen/MSP430/asm-clobbers.ll
===================================================================
--- llvm/test/CodeGen/MSP430/asm-clobbers.ll
+++ llvm/test/CodeGen/MSP430/asm-clobbers.ll
@@ -3,9 +3,52 @@
target datalayout = "e-m:e-p:16:16-i32:16:32-a:16-n8:16"
target triple = "msp430---elf"
-define void @test() {
+define void @test_no_clobber() {
entry:
-; CHECK-LABEL: test:
+; CHECK-LABEL: test_no_clobber
+; CHECK-NOT: push
+ call void asm sideeffect "", ""()
+; CHECK-NOT: pop
+ ret void
+; CHECK: -- End function
+}
+
+define void @test_1() {
+entry:
+; CHECK-LABEL: test_1:
+; CHECK: push r8
+; CHECK: push r6
+; CHECK: push r4
+ call void asm sideeffect "", "~{r4},~{r6},~{r8}"()
+; CHECK: pop r4
+; CHECK: pop r6
+; CHECK: pop r8
+ ret void
+}
+
+define void @test_2() {
+entry:
+; CHECK-LABEL: test_2:
+; CHECK: push r9
+; CHECK: push r7
+; CHECK: push r5
+ call void asm sideeffect "", "~{r5},~{r7},~{r9}"()
+; CHECK: pop r5
+; CHECK: pop r7
+; CHECK: pop r9
+ ret void
+}
+
+; The r10 register is special because the sequence
+; pop r10
+; ret
+; can be replaced with
+; jmp __mspabi_func_epilog_1
+; or other such function (depending on previous instructions).
+; Still, it is not replaced *yet*.
+define void @test_r10() {
+entry:
+; CHECK-LABEL: test_r10:
; CHECK: push r10
call void asm sideeffect "", "~{r10}"()
; CHECK: pop r10
Index: llvm/lib/Target/MSP430/MSP430RegisterInfo.td
===================================================================
--- llvm/lib/Target/MSP430/MSP430RegisterInfo.td
+++ llvm/lib/Target/MSP430/MSP430RegisterInfo.td
@@ -34,7 +34,7 @@
def SPB : MSP430Reg<1, "r1", ["sp"]>;
def SRB : MSP430Reg<2, "r2", ["sr"]>;
def CGB : MSP430Reg<3, "r3", ["cg"]>;
-def FPB : MSP430Reg<4, "r4", ["fp"]>;
+def R4B : MSP430Reg<4, "r4", ["fp"]>;
def R5B : MSP430Reg<5, "r5">;
def R6B : MSP430Reg<6, "r6">;
def R7B : MSP430Reg<7, "r7">;
@@ -54,7 +54,7 @@
def SP : MSP430RegWithSubregs<1, "r1", [SPB], ["sp"]>;
def SR : MSP430RegWithSubregs<2, "r2", [SRB], ["sr"]>;
def CG : MSP430RegWithSubregs<3, "r3", [CGB], ["cg"]>;
-def FP : MSP430RegWithSubregs<4, "r4", [FPB], ["fp"]>;
+def R4 : MSP430RegWithSubregs<4, "r4", [R4B], ["fp"]>;
def R5 : MSP430RegWithSubregs<5, "r5", [R5B]>;
def R6 : MSP430RegWithSubregs<6, "r6", [R6B]>;
def R7 : MSP430RegWithSubregs<7, "r7", [R7B]>;
@@ -72,7 +72,7 @@
// Volatile registers
(add R12B, R13B, R14B, R15B, R11B, R10B, R9B, R8B, R7B, R6B, R5B,
// Frame pointer, sometimes allocable
- FPB,
+ R4B,
// Volatile, but not allocable
PCB, SPB, SRB, CGB)>;
@@ -80,6 +80,6 @@
// Volatile registers
(add R12, R13, R14, R15, R11, R10, R9, R8, R7, R6, R5,
// Frame pointer, sometimes allocable
- FP,
+ R4,
// Volatile, but not allocable
PC, SP, SR, CG)>;
Index: llvm/lib/Target/MSP430/MSP430RegisterInfo.cpp
===================================================================
--- llvm/lib/Target/MSP430/MSP430RegisterInfo.cpp
+++ llvm/lib/Target/MSP430/MSP430RegisterInfo.cpp
@@ -39,7 +39,7 @@
const MSP430FrameLowering *TFI = getFrameLowering(*MF);
const Function* F = &MF->getFunction();
static const MCPhysReg CalleeSavedRegs[] = {
- MSP430::FP, MSP430::R5, MSP430::R6, MSP430::R7,
+ MSP430::R4, MSP430::R5, MSP430::R6, MSP430::R7,
MSP430::R8, MSP430::R9, MSP430::R10,
0
};
@@ -49,7 +49,7 @@
0
};
static const MCPhysReg CalleeSavedRegsIntr[] = {
- MSP430::FP, MSP430::R5, MSP430::R6, MSP430::R7,
+ MSP430::R4, MSP430::R5, MSP430::R6, MSP430::R7,
MSP430::R8, MSP430::R9, MSP430::R10, MSP430::R11,
MSP430::R12, MSP430::R13, MSP430::R14, MSP430::R15,
0
@@ -86,8 +86,8 @@
// Mark frame pointer as reserved if needed.
if (TFI->hasFP(MF)) {
- Reserved.set(MSP430::FPB);
- Reserved.set(MSP430::FP);
+ Reserved.set(MSP430::R4B);
+ Reserved.set(MSP430::R4);
}
return Reserved;
@@ -112,7 +112,7 @@
DebugLoc dl = MI.getDebugLoc();
int FrameIndex = MI.getOperand(FIOperandNum).getIndex();
- unsigned BasePtr = (TFI->hasFP(MF) ? MSP430::FP : MSP430::SP);
+ unsigned BasePtr = (TFI->hasFP(MF) ? MSP430::R4 : MSP430::SP);
int Offset = MF.getFrameInfo().getObjectOffset(FrameIndex);
// Skip the saved PC
@@ -156,5 +156,5 @@
Register MSP430RegisterInfo::getFrameRegister(const MachineFunction &MF) const {
const MSP430FrameLowering *TFI = getFrameLowering(MF);
- return TFI->hasFP(MF) ? MSP430::FP : MSP430::SP;
+ return TFI->hasFP(MF) ? MSP430::R4 : MSP430::SP;
}
Index: llvm/lib/Target/MSP430/MSP430ISelLowering.cpp
===================================================================
--- llvm/lib/Target/MSP430/MSP430ISelLowering.cpp
+++ llvm/lib/Target/MSP430/MSP430ISelLowering.cpp
@@ -1300,7 +1300,7 @@
SDLoc dl(Op); // FIXME probably not meaningful
unsigned Depth = cast<ConstantSDNode>(Op.getOperand(0))->getZExtValue();
SDValue FrameAddr = DAG.getCopyFromReg(DAG.getEntryNode(), dl,
- MSP430::FP, VT);
+ MSP430::R4, VT);
while (Depth--)
FrameAddr = DAG.getLoad(VT, dl, DAG.getEntryNode(), FrameAddr,
MachinePointerInfo());
Index: llvm/lib/Target/MSP430/MSP430FrameLowering.cpp
===================================================================
--- llvm/lib/Target/MSP430/MSP430FrameLowering.cpp
+++ llvm/lib/Target/MSP430/MSP430FrameLowering.cpp
@@ -64,16 +64,16 @@
// Save FP into the appropriate stack slot...
BuildMI(MBB, MBBI, DL, TII.get(MSP430::PUSH16r))
- .addReg(MSP430::FP, RegState::Kill);
+ .addReg(MSP430::R4, RegState::Kill);
// Update FP with the new base value...
- BuildMI(MBB, MBBI, DL, TII.get(MSP430::MOV16rr), MSP430::FP)
+ BuildMI(MBB, MBBI, DL, TII.get(MSP430::MOV16rr), MSP430::R4)
.addReg(MSP430::SP);
// Mark the FramePtr as live-in in every block except the entry.
for (MachineFunction::iterator I = std::next(MF.begin()), E = MF.end();
I != E; ++I)
- I->addLiveIn(MSP430::FP);
+ I->addLiveIn(MSP430::R4);
} else
NumBytes = StackSize - MSP430FI->getCalleeSavedFrameSize();
@@ -132,7 +132,7 @@
NumBytes = FrameSize - CSSize;
// pop FP.
- BuildMI(MBB, MBBI, DL, TII.get(MSP430::POP16r), MSP430::FP);
+ BuildMI(MBB, MBBI, DL, TII.get(MSP430::POP16r), MSP430::R4);
} else
NumBytes = StackSize - CSSize;
@@ -154,7 +154,7 @@
if (MFI.hasVarSizedObjects()) {
BuildMI(MBB, MBBI, DL,
- TII.get(MSP430::MOV16rr), MSP430::SP).addReg(MSP430::FP);
+ TII.get(MSP430::MOV16rr), MSP430::SP).addReg(MSP430::R4);
if (CSSize) {
MachineInstr *MI =
BuildMI(MBB, MBBI, DL,
Index: llvm/lib/Target/MSP430/Disassembler/MSP430Disassembler.cpp
===================================================================
--- llvm/lib/Target/MSP430/Disassembler/MSP430Disassembler.cpp
+++ llvm/lib/Target/MSP430/Disassembler/MSP430Disassembler.cpp
@@ -65,7 +65,7 @@
static const unsigned GR8DecoderTable[] = {
MSP430::PCB, MSP430::SPB, MSP430::SRB, MSP430::CGB,
- MSP430::FPB, MSP430::R5B, MSP430::R6B, MSP430::R7B,
+ MSP430::R4B, MSP430::R5B, MSP430::R6B, MSP430::R7B,
MSP430::R8B, MSP430::R9B, MSP430::R10B, MSP430::R11B,
MSP430::R12B, MSP430::R13B, MSP430::R14B, MSP430::R15B
};
@@ -83,7 +83,7 @@
static const unsigned GR16DecoderTable[] = {
MSP430::PC, MSP430::SP, MSP430::SR, MSP430::CG,
- MSP430::FP, MSP430::R5, MSP430::R6, MSP430::R7,
+ MSP430::R4, MSP430::R5, MSP430::R6, MSP430::R7,
MSP430::R8, MSP430::R9, MSP430::R10, MSP430::R11,
MSP430::R12, MSP430::R13, MSP430::R14, MSP430::R15
};
Index: llvm/lib/Target/MSP430/AsmParser/MSP430AsmParser.cpp
===================================================================
--- llvm/lib/Target/MSP430/AsmParser/MSP430AsmParser.cpp
+++ llvm/lib/Target/MSP430/AsmParser/MSP430AsmParser.cpp
@@ -562,7 +562,7 @@
case MSP430::SP: return MSP430::SPB;
case MSP430::SR: return MSP430::SRB;
case MSP430::CG: return MSP430::CGB;
- case MSP430::FP: return MSP430::FPB;
+ case MSP430::R4: return MSP430::R4B;
case MSP430::R5: return MSP430::R5B;
case MSP430::R6: return MSP430::R6B;
case MSP430::R7: return MSP430::R7B;
Index: clang/test/CodeGen/msp430-register-names.c
===================================================================
--- /dev/null
+++ clang/test/CodeGen/msp430-register-names.c
@@ -0,0 +1,105 @@
+// Registers R0 - R3 have different names inside the LLVM MSP430 target code.
+// Test that they are handled properly when used inside clobber lists.
+// At the time of writing, llc silently ignores unknown register names.
+
+// REQUIRES: msp430-registered-target
+// RUN: %clang -target msp430 -c %s -mllvm -stop-after=finalize-isel -o- | FileCheck %s
+
+void test_function(void) {
+ asm volatile(""
+ :
+ :
+ : "r0");
+ asm volatile(""
+ :
+ :
+ : "r1");
+ asm volatile(""
+ :
+ :
+ : "r2");
+ asm volatile(""
+ :
+ :
+ : "r3");
+ asm volatile(""
+ :
+ :
+ : "r4");
+ asm volatile(""
+ :
+ :
+ : "r5");
+ asm volatile(""
+ :
+ :
+ : "r6");
+ asm volatile(""
+ :
+ :
+ : "r7");
+ asm volatile(""
+ :
+ :
+ : "r8");
+ asm volatile(""
+ :
+ :
+ : "r9");
+ asm volatile(""
+ :
+ :
+ : "r10");
+ asm volatile(""
+ :
+ :
+ : "r11");
+ asm volatile(""
+ :
+ :
+ : "r12");
+ asm volatile(""
+ :
+ :
+ : "r13");
+ asm volatile(""
+ :
+ :
+ : "r14");
+ asm volatile(""
+ :
+ :
+ : "r15");
+ // CHECK: call void asm sideeffect "", "~{pc}"()
+ // CHECK: call void asm sideeffect "", "~{sp}"()
+ // CHECK: call void asm sideeffect "", "~{sr}"()
+ // CHECK: call void asm sideeffect "", "~{cg}"()
+ // CHECK: call void asm sideeffect "", "~{r4}"()
+ // CHECK: call void asm sideeffect "", "~{r5}"()
+ // CHECK: call void asm sideeffect "", "~{r6}"()
+ // CHECK: call void asm sideeffect "", "~{r7}"()
+ // CHECK: call void asm sideeffect "", "~{r8}"()
+ // CHECK: call void asm sideeffect "", "~{r9}"()
+ // CHECK: call void asm sideeffect "", "~{r10}"()
+ // CHECK: call void asm sideeffect "", "~{r11}"()
+ // CHECK: call void asm sideeffect "", "~{r12}"()
+ // CHECK: call void asm sideeffect "", "~{r13}"()
+ // CHECK: call void asm sideeffect "", "~{r14}"()
+ // CHECK: call void asm sideeffect "", "~{r15}"()
+ // CHECK: INLINEASM &"", {{.*}} implicit-def early-clobber $pc
+ // CHECK: INLINEASM &"", {{.*}} implicit-def early-clobber $sp
+ // CHECK: INLINEASM &"", {{.*}} implicit-def early-clobber $sr
+ // CHECK: INLINEASM &"", {{.*}} implicit-def early-clobber $cg
+ // CHECK: INLINEASM &"", {{.*}} implicit-def early-clobber $r4
+ // CHECK: INLINEASM &"", {{.*}} implicit-def early-clobber $r5
+ // CHECK: INLINEASM &"", {{.*}} implicit-def early-clobber $r6
+ // CHECK: INLINEASM &"", {{.*}} implicit-def early-clobber $r7
+ // CHECK: INLINEASM &"", {{.*}} implicit-def early-clobber $r8
+ // CHECK: INLINEASM &"", {{.*}} implicit-def early-clobber $r9
+ // CHECK: INLINEASM &"", {{.*}} implicit-def early-clobber $r10
+ // CHECK: INLINEASM &"", {{.*}} implicit-def early-clobber $r11
+ // CHECK: INLINEASM &"", {{.*}} implicit-def early-clobber $r12
+ // CHECK: INLINEASM &"", {{.*}} implicit-def early-clobber $r13
+ // CHECK: INLINEASM &"", {{.*}} implicit-def early-clobber $r14
+ // CHECK: INLINEASM &"", {{.*}} implicit-def early-clobber $r15
+}
Index: clang/lib/Basic/Targets/MSP430.h
===================================================================
--- clang/lib/Basic/Targets/MSP430.h
+++ clang/lib/Basic/Targets/MSP430.h
@@ -64,8 +64,14 @@
ArrayRef<const char *> getGCCRegNames() const override;
ArrayRef<TargetInfo::GCCRegAlias> getGCCRegAliases() const override {
- // No aliases.
- return None;
+ // Make r0 - r3 be recognized by llc (f.e., in clobber list)
+ static const TargetInfo::GCCRegAlias GCCRegAliases[] = {
+ {{"r0"}, "pc"},
+ {{"r1"}, "sp"},
+ {{"r2"}, "sr"},
+ {{"r3"}, "cg"},
+ };
+ return GCCRegAliases;
}
bool validateAsmConstraint(const char *&Name,
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