[Qemu-devel] [PATCH for-2.4] tcg: correctly mark dead inputs for mov with a constant

[Aurelien Jarno <aurelien@aurel32.net>]

When tcg_reg_alloc_mov propagate a constant, we failed to correctly mark
a temp as dead if the liveness analysis hints so. This fixes the
following assert when configure with --enable-debug-tcg:

  qemu-x86_64: tcg/tcg.c:1827: tcg_reg_alloc_bb_end: Assertion `ts->val_type == TEMP_VAL_DEAD' failed.

Cc: Richard Henderson <rth@twiddle.net>
Reported-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
---
 tcg/tcg.c | 3 +++
 1 file changed, 3 insertions(+)

This is triggered by the patch "tcg/optimize: allow constant to have
copies", but I guess it might be triggered other ways. Therefore it's a 
good candidate for 2.4.

diff --git a/tcg/tcg.c b/tcg/tcg.c
index 7e088b1..9a2508b 100644
--- a/tcg/tcg.c
+++ b/tcg/tcg.c
@@ -1920,6 +1920,9 @@ static void tcg_reg_alloc_mov(TCGContext *s, const TCGOpDef *def,
         }
         ots->val_type = TEMP_VAL_CONST;
         ots->val = ts->val;
+        if (IS_DEAD_ARG(1)) {
+            temp_dead(s, args[1]);
+        }
     } else {
         /* The code in the first if block should have moved the
            temp to a register. */
-- 
2.1.4