gp-relax/lwgp test

[linsinan1995]

• linker.ld for testing patch for gp relaxation does not work for symbols with alignment > 1024 riscv-collab/riscv-gnu-toolchain#497

• prev_linker.ld for testing patch for adding lwgp/ldgp insn

prev_linker.ld

MEMORY {
  SRAM (!RX): ORIGIN = 0x00010000, LENGTH = 0x7fffffff
}

SECTIONS {
  .shmem_buffers : {
    . = ALIGN(2048);
    *(.shmem*)
  } > SRAM
  .sbss : {
    __global_pointer$ = .;
    *(.sbss*)
  } > SRAM
  .sdata : { *(.sdata*) } > SRAM
  .bss : { *(.bss*) } > SRAM
  .data : { *(.data*) } > SRAM
  .text : { *(.text*) } > SRAM
}

linker.ld

MEMORY {
  SRAM (!RX): ORIGIN = 0x00010000, LENGTH = 0x7fffffff
}

SECTIONS {
  .sbss : {
    __global_pointer$ = .;
    *(.sbss*)
  } > SRAM
  .sdata : { *(.sdata*) } > SRAM
  .bss : { *(.bss*) } > SRAM
  .data : { *(.data*) } > SRAM
  .text : { *(.text*) } > SRAM

  .shmem_buffers : {
    . = ALIGN(2048);
    *(.shmem*)
  } > SRAM

}

lwgp

#include <stdint.h>

#include <stdint.h>

#ifdef LWGP
// This one silently makes ld stop relaxing
uint8_t shmem_buf_sram01[16384] __attribute__((aligned(16384), section(".shmem_buffers")));
#elif LDGP
uint8_t shmem_buf_sram02[32768] __attribute__((aligned(32768), section(".shmem_buffers")));
#else
// These are fine
uint8_t shmem_buf_sram03[2048] __attribute__((aligned(2048), section(".shmem_buffers")));
#endif

#ifdef LDGP
__attribute__((aligned(8), section(".sbss"))) uint32_t var_sbss;
__attribute__((aligned(8), section(".sdata"))) uint32_t var_sdata = 1;
#else
__attribute__((section(".sbss"))) uint32_t var_sbss;
__attribute__((section(".sdata"))) uint32_t var_sdata = 1;
#endif

#ifdef TEST_RELOCATION_TO_TRUNCATE
__attribute__((aligned(2), section(".sdata"))) uint16_t var_sdata2 = 1;
__attribute__((section(".sdata"))) uint8_t var_sdata3 = 1;
__attribute__((section(".sdata"))) uint8_t var_sdata4 = 1;
__attribute__((section(".sdata"))) uint32_t var_sdata5 = 1;
__attribute__((section(".sdata"))) uint64_t var_sdata6 = 1;
#endif

uint32_t var_bss[16];
uint32_t var_data[16] = {1};

int main(void)
{
    return var_sbss + var_sdata  + var_bss[0] + var_data[0] 
#ifdef TEST_RELOCATION_TO_TRUNCATE
      + var_sdata2 + var_sdata3 + var_sdata4 + var_sdata5 + var_sdata6
#endif
    ;
}

run.sh
set -e

rm -f lwgp[12345]*
prefix=./../../obj-rv64ic_zceb/bin/riscv64-unknown-elf-

${prefix}gcc -g -c lwgp.c -o lwgp1.o
${prefix}ld -T linker.ld lwgp1.o -o lwgp1
${prefix}objdump -D -S -j.text -M no-aliases lwgp1

${prefix}gcc -g -c lwgp.c -o lwgp2.o -DLWGP
${prefix}ld -T linker.ld lwgp2.o -o lwgp2
${prefix}objdump -Dr -S -j.text -M no-aliases lwgp2

${prefix}gcc -g -c lwgp.c -o lwgp3.o -DLDGP
${prefix}ld -T linker.ld lwgp3.o -o lwgp3
${prefix}objdump -Dr -S -j.text -M no-aliases lwgp3

${prefix}gcc -g -c lwgp.c -o lwgp4.o -DTEST_RELOCATION_TO_TRUNCATE -DLWGP
${prefix}ld -T linker.ld lwgp4.o -o lwgp4
${prefix}objdump -Dr -S -j.text -M no-aliases lwgp4

${prefix}gcc -g -c lwgp.c -o lwgp5.o -DLWGP -DTEST_RELOCATION_TO_TRUNCATE
${prefix}ld -T linker.ld lwgp5.o -o lwgp5
${prefix}objdump -Dr -S -j.text -M no-aliases lwgp5

# test lwgp alignment problem
${prefix}gcc -g -c lwgp.c -o lwgp1.o
${prefix}ld -T prev_linker.ld lwgp1.o -o lwgp1
${prefix}objdump -D -S -j.text -M no-aliases lwgp1

${prefix}gcc -g -c lwgp.c -o lwgp2.o -DLWGP
${prefix}ld -T prev_linker.ld lwgp2.o -o lwgp2
${prefix}objdump -Dr -S -j.text -M no-aliases lwgp2

${prefix}gcc -g -c lwgp.c -o lwgp3.o -DLDGP
${prefix}ld -T prev_linker.ld lwgp3.o -o lwgp3
${prefix}objdump -Dr -S -j.text -M no-aliases lwgp3

${prefix}gcc -g -c lwgp.c -o lwgp4.o -DTEST_RELOCATION_TO_TRUNCATE -DLWGP
${prefix}ld -T prev_linker.ld lwgp4.o -o lwgp4
${prefix}objdump -Dr -S -j.text -M no-aliases lwgp4

${prefix}gcc -g -c lwgp.c -o lwgp5.o -DLWGP -DTEST_RELOCATION_TO_TRUNCATE
${prefix}ld -T prev_linker.ld lwgp5.o -o lwgp5
${prefix}objdump -Dr -S -j.text -M no-aliases lwgp5

[linsinan1995]

trying to fix this issue in branch riscv-binutils-2.37@gp-relaxtion-fix.

got correct result, but also a lot of segfault

0000000000010088 <main>:

uint32_t var_bss[16];
uint32_t var_data[16] = {1};

int main(void)
{
   10088:	1141                	c.addi	sp,-16
   1008a:	e422                	c.sdsp	s0,8(sp)
   1008c:	0800                	c.addi4spn	s0,sp,16
    return var_sbss + var_sdata  + var_bss[0] + var_data[0] 
   1008e:	0001a703          	lw	a4,0(gp) # 10000 <var_sbss>
   10092:	0041a783          	lw	a5,4(gp) # 10004 <var_sdata>
   10096:	9fb9                	c.addw	a5,a4
   10098:	0007871b          	addiw	a4,a5,0
   1009c:	00818793          	addi	a5,gp,8 # 10008 <var_bss>
   100a0:	439c                	c.lw	a5,0(a5)
   100a2:	9fb9                	c.addw	a5,a4
   100a4:	0007871b          	addiw	a4,a5,0
   100a8:	04818793          	addi	a5,gp,72 # 10048 <var_data>
   100ac:	439c                	c.lw	a5,0(a5)
   100ae:	9fb9                	c.addw	a5,a4
   100b0:	2781                	c.addiw	a5,0
   100b2:	2781                	c.addiw	a5,0
#ifdef TEST_RELOCATION_TO_TRUNCATE
      + var_sdata2 + var_sdata3 + var_sdata4 + var_sdata5 + var_sdata6
#endif
    ;
}
   100b4:	853e                	c.mv	a0,a5
   100b6:	6422                	c.ldsp	s0,8(sp)
   100b8:	0141                	c.addi	sp,16
   100ba:	8082                	c.jr	ra

0000000000010088 <main>:
   10088:	1141                	addi	sp,sp,-16
   1008a:	e422                	sd	s0,8(sp)
   1008c:	0800                	addi	s0,sp,16
   1008e:	0001a703          	lw	a4,0(gp) # 10000 <var_sbss>
   10092:	0041a783          	lw	a5,4(gp) # 10004 <var_sdata>
   10096:	9fb9                	addw	a5,a5,a4
   10098:	0007871b          	sext.w	a4,a5
   1009c:	00818793          	addi	a5,gp,8 # 10008 <var_bss>
   100a0:	439c                	lw	a5,0(a5)
   100a2:	9fb9                	addw	a5,a5,a4
   100a4:	0007871b          	sext.w	a4,a5
   100a8:	04818793          	addi	a5,gp,72 # 10048 <var_data>
   100ac:	439c                	lw	a5,0(a5)
   100ae:	9fb9                	addw	a5,a5,a4
   100b0:	2781                	sext.w	a5,a5
   100b2:	2781                	sext.w	a5,a5
   100b4:	853e                	mv	a0,a5
   100b6:	6422                	ld	s0,8(sp)
   100b8:	0141                	addi	sp,sp,16
   100ba:	8082                	ret