On 9/21/21 1:18 PM, WANG Xuerui wrote:
+ /* Test for PC-relative values that can be loaded faster. */
+ intptr_t pc_offset = val - (uintptr_t)s->code_ptr;
This isn't quite right for split r^x code buffer.
You should have seen this with --enable-debug-tcg...
You need pc_offset = tcg_pcrel_diff(s, (void *)val).
+ if (pc_offset == (int32_t)pc_offset) {
+ tcg_target_long lo = sextreg(pc_offset, 0, 12);
+ tcg_target_long hi = pc_offset - lo;
+ tcg_out_opc_pcaddu12i(s, rd, hi >> 12);
And... this doesn't quite work, right at the edges. If lo is negative, hi can overflow
out of range. There are a number of ways to fix this. One is to extract the pieces and
re-assemble to see if it matches. Another is to rearrange the arithmetic just a little
and use PCALAU12I.
+ tcg_target_long upper = (val >> 12) & 0xfffff;
+ tcg_target_long higher = (val >> 32) & 0xfffff;
Better to use extract64(val, 12, 20) and extract64(val, 32, 30).
r~
