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[AArch64] Allow label arithmetic with add/sub/cmp 

Allow instructions such as 'cmp w0, #(end - start)' by folding the
expression into a constant. For ELF, we fold only if the symbols are in
the same section. For MachO, we fold if the expression contains only
symbols that are not linker visible.

Fixes https://llvm.org/bugs/show_bug.cgi?id=18920

Differential Revision: https://reviews.llvm.org/D23834

llvm-svn: 283862
This commit is contained in:
Diana Picus 2016-10-11 09:17:47 +00:00
parent 750f6a780b
commit c93518db8c
8 changed files with 347 additions and 28 deletions
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21
llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp
View File

@ -729,9 +729,13 @@ public:
|| ELFRefKind == AArch64MCExpr::VK_TLSDESC_LO12;
}
// Otherwise it should be a real immediate in range:
const MCConstantExpr *CE = cast<MCConstantExpr>(Expr);
// If it's a constant, it should be a real immediate in range:
if (auto *CE = dyn_cast<MCConstantExpr>(Expr))
return CE->getValue() >= 0 && CE->getValue() <= 0xfff;
// If it's an expression, we hope for the best and let the fixup/relocation
// code deal with it.
return true;
}
bool isAddSubImmNeg() const {
if (!isShiftedImm() && !isImm())
@ -3568,9 +3572,7 @@ bool AArch64AsmParser::validateInstruction(MCInst &Inst,
AArch64MCExpr::VariantKind ELFRefKind;
MCSymbolRefExpr::VariantKind DarwinRefKind;
int64_t Addend;
if (!classifySymbolRef(Expr, ELFRefKind, DarwinRefKind, Addend)) {
return Error(Loc[2], "invalid immediate expression");
}
if (classifySymbolRef(Expr, ELFRefKind, DarwinRefKind, Addend)) {
// Only allow these with ADDXri.
if ((DarwinRefKind == MCSymbolRefExpr::VK_PAGEOFF ||
@ -3591,8 +3593,13 @@ bool AArch64AsmParser::validateInstruction(MCInst &Inst,
Inst.getOpcode() == AArch64::ADDWri))
return false;
// Don't allow expressions in the immediate field otherwise
return Error(Loc[2], "invalid immediate expression");
// Don't allow symbol refs in the immediate field otherwise
// Note: Loc.back() may be Loc[1] or Loc[2] depending on the number of
// operands of the original instruction (i.e. 'add w0, w1, borked' vs
// 'cmp w0, 'borked')
return Error(Loc.back(), "invalid immediate expression");
}
// We don't validate more complex expressions here
}
return false;
}

11
llvm/lib/Target/AArch64/MCTargetDesc/AArch64AsmBackend.cpp
View File

@ -521,6 +521,17 @@ public:
return CompactUnwindEncoding;
}
void processFixupValue(const MCAssembler &Asm, const MCAsmLayout &Layout,
const MCFixup &Fixup, const MCFragment *DF,
const MCValue &Target, uint64_t &Value,
bool &IsResolved) override {
// Try to get the encoded value for the fixup as-if we're mapping it into
// the instruction. This allows adjustFixupValue() to issue a diagnostic
// if the value is invalid.
if (IsResolved)
(void)adjustFixupValue(Fixup, Value, &Asm.getContext());
}
};
} // end anonymous namespace

2
llvm/lib/Target/AArch64/MCTargetDesc/AArch64MachObjectWriter.cpp
View File

@ -75,7 +75,7 @@ bool AArch64MachObjectWriter::getAArch64FixupKindMachOInfo(
Log2Size = llvm::Log2_32(4);
switch (Sym->getKind()) {
default:
llvm_unreachable("Unexpected symbol reference variant kind!");
return false;
case MCSymbolRefExpr::VK_PAGEOFF:
RelocType = unsigned(MachO::ARM64_RELOC_PAGEOFF12);
return true;

5
llvm/test/MC/AArch64/basic-a64-diagnostics.s
View File

@ -172,9 +172,14 @@
// A relocation should be provided for symbols
add x3, x9, #variable
add x3, x9, #variable-16
// CHECK-ERROR: error: expected compatible register, symbol or integer in range [0, 4095]
// CHECK-ERROR-NEXT: add x3, x9, #variable
// CHECK-ERROR-NEXT: ^
// CHECK-ERROR-NEXT: error: expected compatible register, symbol or integer in range [0, 4095]
// CHECK-ERROR-NEXT: add x3, x9, #variable-16
// CHECK-ERROR-NEXT: ^
//------------------------------------------------------------------------------

61
llvm/test/MC/AArch64/label-arithmetic-darwin.s Normal file
View File

@ -0,0 +1,61 @@
// RUN: llvm-mc -triple aarch64-darwin -filetype=obj %s -o - | llvm-objdump -r -d - | FileCheck %s
// RUN: llvm-mc -triple aarch64-ios -filetype=obj %s -o - | llvm-objdump -r -d - | FileCheck %s
visible:
.space 8
Lstart:
.space 8
Lend:
adds w0, w1, #(Lend - Lstart)
adds x0, x1, #(Lend - Lstart)
add w0, w1, #(Lend - Lstart)
add x0, x1, #(Lend - Lstart)
cmp w0, #(Lend - Lstart)
cmp x0, #(Lend - Lstart)
sub w0, w1, #(Lend - Lstart)
sub x0, x1, #(Lend - Lstart)
// CHECK: adds w0, w1, #8
// CHECK: adds x0, x1, #8
// CHECK: add w0, w1, #8
// CHECK: add x0, x1, #8
// CHECK: cmp w0, #8
// CHECK: cmp x0, #8
// CHECK: sub w0, w1, #8
// CHECK: sub x0, x1, #8
add w0, w1, #(Lend - Lstart), lsl #12
cmp w0, #(Lend - Lstart), lsl #12
// CHECK: add w0, w1, #8, lsl #12
// CHECK: cmp w0, #8, lsl #12
add w0, w1, #((Lend - Lstart) >> 2)
cmp w0, #((Lend - Lstart) >> 2)
// CHECK: add w0, w1, #2
// CHECK: cmp w0, #2
add w0, w1, #(Lend - Lstart + 12)
cmp w0, #(Lend - Lstart + 12)
// CHECK: add w0, w1, #20
// CHECK: cmp w0, #20
add w0, w1, #(Lforward - Lend)
cmp w0, #(Lforward - Lend)
// CHECK: add w0, w1, #320
// CHECK: cmp w0, #320
add w0, w1, #(Lstart - visible)
cmp w0, #(Lstart - visible)
// CHECK: add w0, w1, #8
// CHECK: cmp w0, #8
// Add some filler so we don't have to modify #(Lforward - Lend) if we add more
// instructions above
Lfiller:
.space 320 - (Lfiller - Lend)
Lforward:
.space 4
add w0, w1, #(. - Lforward)
cmp w0, #(. - Lforward)
// CHECK: add w0, w1, #4
// CHECK: cmp w0, #8

68
llvm/test/MC/AArch64/label-arithmetic-diags-darwin.s Normal file
View File

@ -0,0 +1,68 @@
// RUN: not llvm-mc -triple aarch64-darwin -filetype=obj %s -o /dev/null 2>&1 | FileCheck %s
// RUN: not llvm-mc -triple aarch64-ios -filetype=obj %s -o /dev/null 2>&1 | FileCheck %s
Lstart:
.space 8
Lend:
add w0, w1, #(Lend - external)
cmp w0, #(Lend - external)
// CHECK: error: unknown AArch64 fixup kind!
// CHECK-NEXT: add w0, w1, #(Lend - external)
// CHECK-NEXT: ^
// CHECK: error: unknown AArch64 fixup kind!
// CHECK-NEXT: cmp w0, #(Lend - external)
// CHECK-NEXT: ^
add w0, w1, #(Lend - var@TLVPPAGEOFF)
cmp w0, #(Lend - var@TLVPPAGEOFF)
// CHECK: error: unknown AArch64 fixup kind!
// CHECK-NEXT: add w0, w1, #(Lend - var@TLVPPAGEOFF)
// CHECK-NEXT: ^
// CHECK: error: unknown AArch64 fixup kind!
// CHECK-NEXT: cmp w0, #(Lend - var@TLVPPAGEOFF)
// CHECK-NEXT: ^
add w0, w1, #(Lstart - Lend)
cmp w0, #(Lstart - Lend)
// CHECK: error: fixup value out of range
// CHECK-NEXT: add w0, w1, #(Lstart - Lend)
// CHECK-NEXT: ^
// CHECK: error: fixup value out of range
// CHECK-NEXT: cmp w0, #(Lstart - Lend)
// CHECK-NEXT: ^
.space 5000
Lfar:
add w0, w1, #(Lfar - Lend)
cmp w0, #(Lfar - Lend)
// CHECK: error: fixup value out of range
// CHECK-NEXT: add w0, w1, #(Lfar - Lend)
// CHECK-NEXT: ^
// CHECK: error: fixup value out of range
// CHECK-NEXT: cmp w0, #(Lfar - Lend)
// CHECK-NEXT: ^
Lprivate1:
.space 8
notprivate:
.space 8
Lprivate2:
add w0, w1, #(Lprivate2 - Lprivate1)
cmp w0, #(Lprivate2 - Lprivate1)
// CHECK: error: unknown AArch64 fixup kind!
// CHECK-NEXT: add w0, w1, #(Lprivate2 - Lprivate1)
// CHECK-NEXT: ^
// CHECK: error: unknown AArch64 fixup kind!
// CHECK-NEXT: cmp w0, #(Lprivate2 - Lprivate1)
// CHECK-NEXT: ^
.section __TEXT, sec_y, regular, pure_instructions
Lend_across_sec:
add w0, w1, #(Lend_across_sec - Lprivate2)
cmp w0, #(Lend_across_sec - Lprivate2)
// CHECK: error: unknown AArch64 fixup kind!
// CHECK-NEXT: add w0, w1, #(Lend_across_sec - Lprivate2)
// CHECK-NEXT: ^
// CHECK: error: unknown AArch64 fixup kind!
// CHECK-NEXT: cmp w0, #(Lend_across_sec - Lprivate2)
// CHECK-NEXT: ^

71
llvm/test/MC/AArch64/label-arithmetic-diags-elf.s Normal file
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@ -0,0 +1,71 @@
// RUN: not llvm-mc -triple aarch64-elf -filetype=obj %s -o /dev/null 2>&1 | FileCheck %s
.section sec_x
start:
.space 5000
end:
add w0, w1, #(end - start)
cmp w0, #(end - start)
// CHECK: error: fixup value out of range
// CHECK-NEXT: add w0, w1, #(end - start)
// CHECK-NEXT: ^
// CHECK: error: fixup value out of range
// CHECK-NEXT: cmp w0, #(end - start)
// CHECK-NEXT: ^
negative:
add w0, w1, #(end - negative)
cmp w0, #(end - negative)
// CHECK: error: fixup value out of range
// CHECK-NEXT: add w0, w1, #(end - negative)
// CHECK-NEXT: ^
// CHECK: error: fixup value out of range
// CHECK-NEXT: cmp w0, #(end - negative)
// CHECK-NEXT: ^
add w0, w1, #(end - external)
cmp w0, #(end - external)
// CHECK: error: symbol 'external' can not be undefined in a subtraction expression
// CHECK-NEXT: add w0, w1, #(end - external)
// CHECK-NEXT: ^
// CHECK: error: symbol 'external' can not be undefined in a subtraction expression
// CHECK-NEXT: cmp w0, #(end - external)
// CHECK-NEXT: ^
add w0, w1, #:lo12:external - end
cmp w0, #:lo12:external - end
// CHECK: error: Unsupported pc-relative fixup kind
// CHECK-NEXT: add w0, w1, #:lo12:external - end
// CHECK-NEXT: ^
// CHECK: error: Unsupported pc-relative fixup kind
// CHECK-NEXT: cmp w0, #:lo12:external - end
// CHECK-NEXT: ^
add w0, w1, #:got_lo12:external - end
cmp w0, #:got_lo12:external - end
// CHECK: error: Unsupported pc-relative fixup kind
// CHECK-NEXT: add w0, w1, #:got_lo12:external - end
// CHECK-NEXT: ^
// CHECK: error: Unsupported pc-relative fixup kind
// CHECK-NEXT: cmp w0, #:got_lo12:external - end
// CHECK-NEXT: ^
.section sec_y
end_across_sec:
add w0, w1, #(end_across_sec - start)
cmp w0, #(end_across_sec - start)
// CHECK: error: Cannot represent a difference across sections
// CHECK-NEXT: add w0, w1, #(end_across_sec - start)
// CHECK-NEXT: ^
// CHECK: error: Cannot represent a difference across sections
// CHECK-NEXT: cmp w0, #(end_across_sec - start)
// CHECK-NEXT: ^
add w0, w1, #(sec_y - sec_x)
cmp w0, #(sec_y - sec_x)
// CHECK: error: symbol 'sec_x' can not be undefined in a subtraction expression
// CHECK-NEXT: add w0, w1, #(sec_y - sec_x)
// CHECK-NEXT: ^
// CHECK: error: symbol 'sec_x' can not be undefined in a subtraction expression
// CHECK-NEXT: cmp w0, #(sec_y - sec_x)
// CHECK-NEXT: ^

96
llvm/test/MC/AArch64/label-arithmetic-elf.s Normal file
View File

@ -0,0 +1,96 @@
// RUN: llvm-mc -triple aarch64-elf -filetype=obj %s -o - | llvm-objdump -d - | FileCheck %s
start:
.space 8
end:
// CHECK-LABEL: end:
adds w0, w1, #(end - start)
adds x0, x1, #(end - start)
add w0, w1, #(end - start)
add x0, x1, #(end - start)
cmp w0, #(end - start)
cmp x0, #(end - start)
sub w0, w1, #(end - start)
sub x0, x1, #(end - start)
// CHECK: adds w0, w1, #8
// CHECK: adds x0, x1, #8
// CHECK: add w0, w1, #8
// CHECK: add x0, x1, #8
// CHECK: cmp w0, #8
// CHECK: cmp x0, #8
// CHECK: sub w0, w1, #8
// CHECK: sub x0, x1, #8
add w0, w1, #(end - start), lsl #12
cmp w0, #(end - start), lsl #12
// CHECK: add w0, w1, #8, lsl #12
// CHECK: cmp w0, #8, lsl #12
add w0, w1, #((end - start) >> 2)
cmp w0, #((end - start) >> 2)
// CHECK: add w0, w1, #2
// CHECK: cmp w0, #2
add w0, w1, #(end - start + 12)
cmp w0, #(end - start + 12)
// CHECK: add w0, w1, #20
// CHECK: cmp w0, #20
add w0, w1, #(forward - end)
cmp w0, #(forward - end)
// CHECK: add w0, w1, #320
// CHECK: cmp w0, #320
// Add some filler so we don't have to modify #(forward - end) if we add more
// instructions above
.Lfiller:
.space 320 - (.Lfiller - end)
forward:
.space 8
.Lstart:
.space 8
.Lend:
add w0, w1, #(.Lend - .Lstart)
cmp w0, #(.Lend - .Lstart)
// CHECK: add w0, w1, #8
// CHECK: cmp w0, #8
.Lprivate1:
.space 8
notprivate:
.space 8
.Lprivate2:
add w0, w1, #(.Lprivate2 - .Lprivate1)
cmp w0, #(.Lprivate2 - .Lprivate1)
// CHECK: add w0, w1, #16
// CHECK: cmp w0, #16
.type foo, @function
foo:
// CHECK-LABEL: foo:
add w0, w1, #(foo - .Lprivate2)
cmp w0, #(foo - .Lprivate2)
// CHECK: add w0, w1, #8
// CHECK: cmp w0, #8
ret
.type goo, @function
goo:
// CHECK-LABEL: goo:
add w0, w1, #(goo - foo)
cmp w0, #(goo - foo)
// CHECK: add w0, w1, #12
// CHECK: cmp w0, #12
add w0, w1, #(. - goo)
cmp w0, #(. - goo)
// CHECK: add w0, w1, #8
// CHECK: cmp w0, #12
ret