[Qemu-devel] [PATCH] tcg/ppc: Fix failure in tcg_out_mem_long

[Richard Henderson]

With rt != r0 on loads, we use rt for scratch.  If we need an index
register different from base, we can't use rt, but r0 is usable.

Signed-off-by: Richard Henderson <address@hidden>
---
This ought to fix the problem that Greg reported.

That we need to use --enable-debug-tcg to see the assert, and that I
didn't previously do testing with that is disappointing.  I'm thinking
that we ought to do something like gcc wrt --enable-checking=release
vs development, so that we can't do normal development withing these
asserts enabled.  More on that later...


r~
---
 tcg/ppc/tcg-target.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tcg/ppc/tcg-target.c b/tcg/ppc/tcg-target.c
index c83fd9f..dd84e76 100644
--- a/tcg/ppc/tcg-target.c
+++ b/tcg/ppc/tcg-target.c
@@ -805,7 +805,10 @@ static void tcg_out_mem_long(TCGContext *s, int opi, int 
opx, TCGReg rt,
 
     /* For unaligned, or very large offsets, use the indexed form.  */
     if (offset & align || offset != (int32_t)offset) {
-        tcg_debug_assert(rs != base && (!is_store || rs != rt));
+        if (rs == base) {
+            rs = TCG_REG_R0;
+        }
+        tcg_debug_assert(!is_store || rs != rt);
         tcg_out_movi(s, TCG_TYPE_PTR, rs, orig);
         tcg_out32(s, opx | TAB(rt, base, rs));
         return;
-- 
1.9.3