diff mbox series

[v2,7/8] target/ppc: Zero second doubleword of VSR registers for FPR insns

Message ID 20220906125523.38765-8-victor.colombo@eldorado.org.br
State New
Headers show
Series Multiple ppc instructions fixes | expand

Commit Message

Víctor Colombo Sept. 6, 2022, 12:55 p.m. UTC 
FPR register are mapped to the first doubleword of the VSR registers.
Since PowerISA v3.1, the second doubleword of the target register
must be zeroed for FP instructions.

This patch does it by writting 0 to the second dw everytime the
first dw is being written using set_fpr.

Signed-off-by: Víctor Colombo <victor.colombo@eldorado.org.br>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 target/ppc/translate.c | 8 ++++++++
 1 file changed, 8 insertions(+)
diff mbox series

Patch

diff --git a/target/ppc/translate.c b/target/ppc/translate.c
index 000b1e518d..5e433315e1 100644
--- a/target/ppc/translate.c
+++ b/target/ppc/translate.c
@@ -6443,6 +6443,14 @@  static inline void get_fpr(TCGv_i64 dst, int regno)
 static inline void set_fpr(int regno, TCGv_i64 src)
 {
     tcg_gen_st_i64(src, cpu_env, fpr_offset(regno));
+    /*
+     * Before PowerISA v3.1 the result of doubleword 1 of the VSR
+     * corresponding to the target FPR was undefined. However,
+     * most (if not all) real hardware were setting the result to 0.
+     * Starting at ISA v3.1, the result for doubleword 1 is now defined
+     * to be 0.
+     */
+    tcg_gen_st_i64(tcg_constant_i64(0), cpu_env, vsr64_offset(regno, false));
 }
 
 static inline void get_avr64(TCGv_i64 dst, int regno, bool high)