[lld] [lld] Support thumb PLTs (PR #86223)
Fangrui Song via llvm-commits
llvm-commits at lists.llvm.org
Tue May 28 12:49:45 PDT 2024
================
@@ -231,36 +231,71 @@ static void writePltHeaderLong(uint8_t *buf) {
// The default PLT header requires the .got.plt to be within 128 Mb of the
// .plt in the positive direction.
void ARM::writePltHeader(uint8_t *buf) const {
- // Use a similar sequence to that in writePlt(), the difference is the calling
- // conventions mean we use lr instead of ip. The PLT entry is responsible for
- // saving lr on the stack, the dynamic loader is responsible for reloading
- // it.
- const uint32_t pltData[] = {
- 0xe52de004, // L1: str lr, [sp,#-4]!
- 0xe28fe600, // add lr, pc, #0x0NN00000 &(.got.plt - L1 - 4)
- 0xe28eea00, // add lr, lr, #0x000NN000 &(.got.plt - L1 - 4)
- 0xe5bef000, // ldr pc, [lr, #0x00000NNN] &(.got.plt -L1 - 4)
- };
-
- uint64_t offset = in.gotPlt->getVA() - in.plt->getVA() - 4;
- if (!llvm::isUInt<27>(offset)) {
- // We cannot encode the Offset, use the long form.
- writePltHeaderLong(buf);
- return;
+ if (!config->armThumbPLTs) {
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MaskRay wrote:
When the then/else branches are equally long, we prefer `if (XXX)` to `if (!XXX)`.
https://github.com/llvm/llvm-project/pull/86223
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