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| author | Fangrui Song <maskray@google.com> | 2020-01-20 14:57:11 -0800 |
|---|---|---|
| committer | Fangrui Song <maskray@google.com> | 2020-01-24 10:38:40 -0800 |
| commit | bf04730dee1b74c8e7661c671484eff93c1f5a77 (patch) | |
| tree | 2a780731504023d8075ca85e50e5f582ffd930c6 /lldb/packages/Python/lldbsuite/test/lang/cpp/bitfields/main.cpp | |
| parent | 0e2eea29cc4f360fc95638fbfc8aca24cec3fc5f (diff) | |
| download | bcm5719-llvm-bf04730dee1b74c8e7661c671484eff93c1f5a77.tar.gz bcm5719-llvm-bf04730dee1b74c8e7661c671484eff93c1f5a77.zip | |
Add function attribute "patchable-function-prefix" to support -fpatchable-function-entry=N,M where M>0
Similar to the function attribute `prefix` (prefix data),
"patchable-function-prefix" inserts data (M NOPs) before the function
entry label.
-fpatchable-function-entry=2,1 (1 NOP before entry, 1 NOP after entry)
will look like:
```
.type foo,@function
.Ltmp0: # @foo
nop
foo:
.Lfunc_begin0:
# optional `bti c` (AArch64 Branch Target Identification) or
# `endbr64` (Intel Indirect Branch Tracking)
nop
.section __patchable_function_entries,"awo",@progbits,get,unique,0
.p2align 3
.quad .Ltmp0
```
-fpatchable-function-entry=N,0 + -mbranch-protection=bti/-fcf-protection=branch has two reasonable
placements (https://gcc.gnu.org/ml/gcc-patches/2020-01/msg01185.html):
```
(a) (b)
func: func:
.Ltmp0: bti c
bti c .Ltmp0:
nop nop
```
(a) needs no additional code. If the consensus is to go for (b), we will
need more code in AArch64BranchTargets.cpp / X86IndirectBranchTracking.cpp .
Differential Revision: https://reviews.llvm.org/D73070
(cherry picked from commit 22467e259507f5ead2a87d989251b4c951a587e4)
Diffstat (limited to 'lldb/packages/Python/lldbsuite/test/lang/cpp/bitfields/main.cpp')
0 files changed, 0 insertions, 0 deletions
