[Bug target/84790] Miscompilation for MIPS16 with -fpic and -Os or -O2

[syq at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84790

--- Comment #12 from YunQiang Su <syq at gcc dot gnu.org> ---
You are right: the decision to use $6 is too late.
So let's force to use it in expand pass.

```
diff --git a/gcc/config/mips/mips.cc b/gcc/config/mips/mips.cc
index b63d40a357b..84ff29cd62b 100644
--- a/gcc/config/mips/mips.cc
+++ b/gcc/config/mips/mips.cc
@@ -3318,7 +3318,11 @@ mips16_gp_pseudo_reg (void)
     {
       rtx_insn *scan;

-      cfun->machine->mips16_gp_pseudo_rtx = gen_reg_rtx (Pmode);
+      if (TARGET_USE_GOT)
+       cfun->machine->mips16_gp_pseudo_rtx
+               = gen_rtx_REG (Pmode, POST_CALL_TMP_REG);
+      else
+       cfun->machine->mips16_gp_pseudo_rtx = gen_reg_rtx (Pmode);

       push_topmost_sequence ();


```