riscv64: fix fesetenv(FE_DFL_ENV) crash

When FE_DFL_ENV is passed to fesetenv(), the very first instruction
lw t1, 0(a0) will fail since a0 is -1.

diff --git a/src/fenv/riscv64/fenv.S b/src/fenv/riscv64/fenv.S
index f149003d2eeade71c05fd188d913d2256f918f43..0ea78bf9ac8da26706215e4696a5d865c830e2c1 100644 (file)
--- a/src/fenv/riscv64/fenv.S
+++ b/src/fenv/riscv64/fenv.S
@@ -45,8 +45,11 @@ fegetenv:
 .global fesetenv
 .type fesetenv, %function
 fesetenv:
+       li t2, -1
+       li t1, 0
+       beq a0, t2, 1f
        lw t1, 0(a0)
-       fscsr t0, t1
+1:     fscsr t1
        li a0, 0
        ret