summary refs log tree commit diff stats
path: root/gitlab/issues_text/target_riscv/host_missing/accel_TCG/2371
diff options
context:
space:
mode:
Diffstat (limited to 'gitlab/issues_text/target_riscv/host_missing/accel_TCG/2371')
-rw-r--r--gitlab/issues_text/target_riscv/host_missing/accel_TCG/237152
1 files changed, 0 insertions, 52 deletions
diff --git a/gitlab/issues_text/target_riscv/host_missing/accel_TCG/2371 b/gitlab/issues_text/target_riscv/host_missing/accel_TCG/2371
deleted file mode 100644
index fc11ba171..000000000
--- a/gitlab/issues_text/target_riscv/host_missing/accel_TCG/2371
+++ /dev/null
@@ -1,52 +0,0 @@
-A bug in RISC-V froundnx.h instruction
-Description of problem:
-According to the RISCV ISA manual, the froundnx.h instruction rounds a half-precision floating-point number in the source register to an integer and writes the integer, represented as a half-precision floating-point number, to the destination register. Because the values are stored in 64-bit width registers, they must be NaN-unboxed/boxed before/after the operation. When an input value lacks the proper form of NaN-boxing, it should be treated as a canonical NaN.
-However, when an incorrectly NaN-boxed value is passed to froundnx.h, QEMU produces 0 instead of the canonical NaN. This is because there is a typo in the definition of helper_froundnx_h:
-```
-// target/riscv/fpu_helper.c
-uint64_t helper_froundnx_h(CPURISCVState *env, uint64_t rs1)
-{
-    float16 frs1 = check_nanbox_s(env, rs1); // This should be check_nanbox_h.
-    frs1 = float16_round_to_int(frs1, &env->fp_status);
-    return nanbox_h(env, frs1);
-}
-```
-Steps to reproduce:
-1. Write `test.c`.
-```
-#include <stdio.h>
-
-char i_F6[8] = { 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0 };
-char o_F5[8];
-
-void __attribute__ ((noinline)) show_state() {
-    for (int i = 0; i < 8; i++) {
-        printf("%02x ", o_F5[i]);
-    }
-    printf("\n");
-}
-
-void __attribute__ ((noinline)) run() {
-    __asm__ (
-        "lui t5, %hi(i_F6)\n"
-        "addi t5, t5, %lo(i_F6)\n"
-        "fld ft6, 0(t5)\n"
-        ".insn 0x445372d3\n" // froundnx.h ft5, ft6
-        "lui t5, %hi(o_F5)\n"
-        "addi t5, t5, %lo(o_F5)\n"
-        "fsd ft5, 0(t5)\n"
-    );
-}
-
-int main(int argc, char **argv) {
-    run();
-    show_state();
-
-    return 0;
-}
-```
-2. Compile `test.bin` using this command: `riscv64-linux-gnu-gcc-12 -O2 -no-pie -march=rv64iv ./test.c -o ./test.bin`.
-3. Run QEMU using this command: `qemu-riscv64 -L /usr/riscv64-linux-gnu/ ./test.bin`.
-4. The program, runs on top of the buggy QEMU, prints `00 00 ff ff ff ff ff ff`. It should print `00 7e ff ff ff ff ff ff` after the bug is fixed.
-Additional information:
-