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Merged
deadprogram merged 1 commit into from
Dec 24, 2019
Merged

riscv: improve startup assembly #806

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13 changes: 6 additions & 7 deletions src/device/riscv/start.S
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Original file line number Diff line number Diff line change
Expand Up @@ -3,11 +3,10 @@
.type _start,@function

_start:
// Workaround for missing support of the la pseudo-instruction in Clang 8:
// https://reviews.llvm.org/D55325
lui sp, %hi(_stack_top)
addi sp, sp, %lo(_stack_top)
// see https://gnu-mcu-eclipse.github.io/arch/riscv/programmer/#the-gp-global-pointer-register
lui gp, %hi(__global_pointer$)
addi gp, gp, %lo(__global_pointer$)
// Load the stack pointer.
la sp, _stack_top
// Load the globals pointer. The program will load pointers relative to this
// register, so it must be set to the right value on startup.
// See: https://gnu-mcu-eclipse.github.io/arch/riscv/programmer/#the-gp-global-pointer-register
la gp, __global_pointer$
call main