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[lld-macho] Handle LOH_ARM64_ADRP_LDR_GOT optimization hints

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This hint instructs the linker to perform the AdrpLdr or AdrpAdd
transformation depending on whether the GOT load has been relaxed to
load a local symbol's address.

Differential Revision: https://reviews.llvm.org/D129059
This commit is contained in:
Daniel Bertalan 2022-07-03 10:58:39 +02:00
parent 3e01af093f
commit 2028fe6fbc
2 changed files with 50 additions and 1 deletions
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16
lld/MachO/Arch/ARM64.cpp
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@ -189,6 +189,7 @@ public:
void applyAdrpAdd(const OptimizationHint &);
void applyAdrpAdrp(const OptimizationHint &);
void applyAdrpLdr(const OptimizationHint &);
void applyAdrpLdrGot(const OptimizationHint &);
private:
uint8_t *buf;
@ -424,6 +425,19 @@ void OptimizationHintContext::applyAdrpLdr(const OptimizationHint &hint) {
writeLiteralLdr(buf + hint.offset0 + hint.delta[0], ldr, delta);
}
// GOT loads are emitted by the compiler as a pair of adrp and ldr instructions,
// but they may be changed to adrp+add by relaxGotLoad(). This hint performs
// the AdrpLdr or AdrpAdd transformation depending on whether it was relaxed.
void OptimizationHintContext::applyAdrpLdrGot(const OptimizationHint &hint) {
uint32_t ins2 = read32le(buf + hint.offset0 + hint.delta[0]);
Add add;
Ldr ldr;
if (parseAdd(ins2, add))
applyAdrpAdd(hint);
else if (parseLdr(ins2, ldr))
applyAdrpLdr(hint);
}
void ARM64::applyOptimizationHints(uint8_t *buf, const ConcatInputSection *isec,
ArrayRef<uint64_t> relocTargets) const {
assert(isec);
@ -452,7 +466,7 @@ void ARM64::applyOptimizationHints(uint8_t *buf, const ConcatInputSection *isec,
ctx1.applyAdrpAdd(hint);
break;
case LOH_ARM64_ADRP_LDR_GOT:
// TODO: Implement this as well
ctx1.applyAdrpLdrGot(hint);
break;
}
}

35
lld/test/MachO/loh-adrp-ldr-got.s Normal file
View file

@ -0,0 +1,35 @@
# REQUIRES: aarch64
# RUN: rm -rf %t; split-file %s %t
# RUN: llvm-mc -filetype=obj -triple=arm64-apple-darwin %t/obj.s -o %t/obj.o
# RUN: llvm-mc -filetype=obj -triple=arm64-apple-darwin %t/dylib.s -o %t/dylib.o
# RUN: %lld -arch arm64 -dylib -o %t/libdylib.dylib %t/dylib.o
# RUN: %lld -arch arm64 %t/obj.o %t/libdylib.dylib -o %t/AdrpLdrGot
# RUN: llvm-objdump -d --macho %t/AdrpLdrGot | FileCheck %s
#--- obj.s
.text
.globl _main
# CHECK-LABEL: _main:
_main:
## The referenced symbol is local
L1: adrp x0, _local@GOTPAGE
L2: ldr x0, [x0, _local@GOTPAGEOFF]
# CHECK-NEXT: adr x0
# CHECK-NEXT: nop
## The referenced symbol is in a dylib
L3: adrp x1, _external@GOTPAGE
L4: ldr x1, [x1, _external@GOTPAGEOFF]
# CHECK-NEXT: nop
# CHECK-NEXT: ldr x1
_local:
nop
.loh AdrpLdrGot L1, L2
.loh AdrpLdrGot L3, L4
#--- dylib.s
.globl _external
_external: