https://sourceware.org/bugzilla/show_bug.cgi?id=31175
Bug ID: 31175
Summary: RISCV load immediate relaxation leaves redundant addi
Product: binutils
Version: 2.39
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: ld
Assignee: unassigned at sourceware dot org
Reporter: iwfinlay at gmail dot com
Target Milestone: ---
Created attachment 15261
--> https://sourceware.org/bugzilla/attachment.cgi?id=15261&action=edit
Tar of --save-temps and source to build image
Per the GCC g++ feedback (originally filed there), linker relaxation should
remove the addi/mv in the cases 1, 2, 3. The following is an excerpt from
objdump of the ELF.
20010064 <_Z6globalv>:
20010064: 80000537 lui a0,0x80000
20010068: 00050513 mv a0,a0 <-- (1)
2001006c: 00008067 ret
20010070 <_Z4initv>:
20010070: 800007b7 lui a5,0x80000
20010074: 00078793 mv a5,a5 <-- (2)
20010078: 3e700713 li a4,999
2001007c: 00e7a223 sw a4,4(a5) # 80000004
<__global_pointer$+0xfffff804>
20010080: 0ea00713 li a4,234
20010084: 00e7a423 sw a4,8(a5)
20010088: 00008067 ret
2001008c <_Z5pcnt0v>:
2001008c: 800007b7 lui a5,0x80000
20010090: 00078793 mv a5,a5 <-- (3)
20010094: 0047a703 lw a4,4(a5) # 80000004
<__global_pointer$+0xfffff804>
20010098: 60271713 cpop a4,a4
Command line:
riscv64-unknown-elf-g++ --save-temps -march=rv32imv_zbb_zbs -mabi=ilp32 -O3
-Wall -Wextra -o relax.elf main.cpp test.cpp startup.cpp -fno-builtin -static
-fno-common -mcmodel=medlow -nostdlib -T link.ld
riscv64-unknown-elf-objdump -d relax.elf > relax.disasm
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