On Fri, 2024-01-05 at 20:45 +0800, chenglulu wrote:
>
> 在 2024/1/5 下午7:55, Xi Ruoyao 写道:
> > On Fri, 2024-01-05 at 18:25 +0800, Xi Ruoyao wrote:
> > > On Fri, 2024-01-05 at 17:57 +0800, chenglulu wrote:
> > > > 在 2024/1/5 下午4:37, Xi Ruoyao 写道:
> > > > > On Fri, 2024-01-05 at 11:40 +0800, Lulu Cheng wrote:
> > > > > > bool
> > > > > > loongarch_explicit_relocs_p (enum loongarch_symbol_type type)
> > > > > > {
> > > > > > + /* Instructions pcalau12i, addi.d, lu32i.d and lu52i.d must be
> > > > > > adjancent
> > > > > > + so that the linker can infer the PC of pcalau12i to apply
> > > > > > relocations
> > > > > > + to lu32i.d and lu52i.d. Otherwise, the results would be
> > > > > > incorrect if
> > > > > > + these four instructions are not in the same 4KiB page.
> > > > > > + Therefore, macro instructions are used when cmodel=extreme.
> > > > > > */
> > > > > > + if (loongarch_symbol_extreme_p (type))
> > > > > > + return false;
> > > > > I think this is a bit of strange. With
> > > > > -mexplicit-relocs={auto,always}
> > > > > we should still use explicit relocs, but coding all 4 instructions
> > > > > altogether as
> > > > >
> > > > > "pcalau12i.d\t%1,%pc64_hi12(%2)\n\taddi.d\t%0,$r0,%pclo12(%2)\n\tlu32i.d\t%0,%pc64_lo20(%2)\n\tlu52i.d\t%0,%0,%pc64_hi12(%2)"
> > > > >
> > > > > Give me several hours trying to implement this...
> > > > >
> > > > I think there is no difference between macros and these instructions put
> > > > together. If implement it in a split form, I think I can try it through
> > > > TARGET_SCHED_MACRO_FUSION_PAIR_P
> > We don't need to split the insn. We can just add a "large insn"
> > containing the assembly output we want.
> >
> > See the attached patch. Note that TLS LE/LD/GD needs a fix too because
> > they are basically an variation of GOT addressing.
> >
> > I've ran some small tests and now trying to bootstrap GCC with -
> > mcmodel=extreme in BOOT_CFLAGS...
> >
> > > There is a difference:
> > >
> > > int x;
> > > int t() { return x; }
> > >
> > > pcalau12i.d t0, %pc_hi20(x)
> > > addi.d t1, r0, %pc_lo12(x)
> > > lu32i.d t1, %pc64_lo20(x)
> > > lu52i.d t1, t1, %pc64_hi12(x)
> > > ldx.w a0, t0, t1
> > >
> > > is slightly better than
> > >
> > > pcalau12i.d t0, %pc_hi20(x)
> > > addi.d t1, r0, %pc_lo12(x)
> > > lu32i.d t1, %pc64_lo20(x)
> > > lu52i.d t1, t1, %pc64_hi12(x)
> > > addi.d t0, t0, t1
> > > ld.w a0, t0, 0
> > >
> > > And generating macros when -mexplicit-relocs=always can puzzle people
> > > (it says "always" :-\ ).
> > >
> Thumbs up! This method is much better than my method, I learned
> something! grateful!
> But I still have to test the accuracy.
I found an issue bootstrapping GCC with -mcmodel=extreme in BOOT_CFLAGS:
we need a target hook to tell the generic code
UNSPEC_LA_PCREL_64_PART{1,2} are just a wrapper around symbols, or we'll
see millions lines of messages like
../../gcc/gcc/tree.h:4171:1: note: non-delegitimized UNSPEC
UNSPEC_LA_PCREL_64_PART1 (42) found in variable location
diff --git a/gcc/config/loongarch/loongarch.cc
b/gcc/config/loongarch/loongarch.cc
index 4f89c4af323..410e1b5e693 100644
--- a/gcc/config/loongarch/loongarch.cc
+++ b/gcc/config/loongarch/loongarch.cc
@@ -10868,6 +10868,24 @@ loongarch_asm_code_end (void)
#undef DUMP_FEATURE
}
+static rtx loongarch_delegitimize_address (rtx op)
+{
+ if (GET_CODE (op) == UNSPEC)
+ {
+ int unspec = XINT (op, 1);
+ switch (unspec)
+ {
+ case UNSPEC_LA_PCREL_64_PART1:
+ case UNSPEC_LA_PCREL_64_PART2:
+ return XVECEXP (op, 0, 0);
+ default:
+ return op;
+ }
+ }
+
+ return op;
+}
+
/* Initialize the GCC target structure. */
#undef TARGET_ASM_ALIGNED_HI_OP
#define TARGET_ASM_ALIGNED_HI_OP "\t.half\t"
@@ -11129,6 +11147,10 @@ loongarch_asm_code_end (void)
#define TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT \
loongarch_builtin_support_vector_misalignment
+#undef TARGET_DELEGITIMIZE_ADDRESS
+#define TARGET_DELEGITIMIZE_ADDRESS \
+ loongarch_delegitimize_address
+
struct gcc_target targetm = TARGET_INITIALIZER;
#include "gt-loongarch.h"
--
Xi Ruoyao <xry...@xry111.site>
School of Aerospace Science and Technology, Xidian University
