[Qemu-devel] [PATCH for-2.5 04/10] tcg/optimize: allow constant to have copies

[Aurelien Jarno]

Now that copies and constants are tracked separately, we can allow
constant to have copies, deferring the choice to use a register or a
constant to the register allocation pass. This prevent this kind of
regular constant reloading:

-OUT: [size=338]
+OUT: [size=298]
   mov    -0x4(%r14),%ebp
   test   %ebp,%ebp
   jne    0x7ffbe9cb0ed6
   mov    $0x40002219f8,%rbp
   mov    %rbp,(%r14)
-  mov    $0x40002219f8,%rbp
   mov    $0x4000221a20,%rbx
   mov    %rbp,(%rbx)
   mov    $0x4000000000,%rbp
   mov    %rbp,(%r14)
-  mov    $0x4000000000,%rbp
   mov    $0x4000221d38,%rbx
   mov    %rbp,(%rbx)
   mov    $0x40002221a8,%rbp
   mov    %rbp,(%r14)
-  mov    $0x40002221a8,%rbp
   mov    $0x4000221d40,%rbx
   mov    %rbp,(%rbx)
   mov    $0x4000019170,%rbp
   mov    %rbp,(%r14)
-  mov    $0x4000019170,%rbp
   mov    $0x4000221d48,%rbx
   mov    %rbp,(%rbx)
   mov    $0x40000049ee,%rbp
   mov    %rbp,0x80(%r14)
   mov    %r14,%rdi
   callq  0x7ffbe99924d0
   mov    $0x4000001680,%rbp
   mov    %rbp,0x30(%r14)
   mov    0x10(%r14),%rbp
   mov    $0x4000001680,%rbp
   mov    %rbp,0x30(%r14)
   mov    0x10(%r14),%rbp
   shl    $0x20,%rbp
   mov    (%r14),%rbx
   mov    %ebx,%ebx
   mov    %rbx,(%r14)
   or     %rbx,%rbp
   mov    %rbp,0x10(%r14)
   mov    %rbp,0x90(%r14)
   mov    0x60(%r14),%rbx
   mov    %rbx,0x38(%r14)
   mov    0x28(%r14),%rbx
   mov    $0x4000220e60,%r12
   mov    %rbx,(%r12)
   mov    $0x40002219c8,%rbx
   mov    %rbp,(%rbx)
   mov    0x20(%r14),%rbp
   sub    $0x8,%rbp
   mov    $0x4000004a16,%rbx
   mov    %rbx,0x0(%rbp)
   mov    %rbp,0x20(%r14)
   mov    $0x19,%ebp
   mov    %ebp,0xa8(%r14)
   mov    $0x4000015110,%rbp
   mov    %rbp,0x80(%r14)
   xor    %eax,%eax
   jmpq   0x7ffbebcae426
   lea    -0x5f6d72a(%rip),%rax        # 0x7ffbe3d437b3
   jmpq   0x7ffbebcae426

Cc: Richard Henderson <r...@twiddle.net>
Signed-off-by: Aurelien Jarno <aurel...@aurel32.net>
---
 tcg/optimize.c | 11 ++---------
 1 file changed, 2 insertions(+), 9 deletions(-)

diff --git a/tcg/optimize.c b/tcg/optimize.c
index f16eb1e..48103b2 100644
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -237,11 +237,6 @@ static void tcg_opt_gen_mov(TCGContext *s, TCGOp *op, 
TCGArg *args,
         return;
     }
 
-    if (temp_is_const(src)) {
-        tcg_opt_gen_movi(s, op, args, dst, temps[src].val);
-        return;
-    }
-
     TCGOpcode new_op = op_to_mov(op->opc);
     tcg_target_ulong mask;
 
@@ -255,17 +250,15 @@ static void tcg_opt_gen_mov(TCGContext *s, TCGOp *op, 
TCGArg *args,
     }
     temps[dst].mask = mask;
 
-    assert(!temp_is_const(src));
-
     if (s->temps[src].type == s->temps[dst].type) {
         if (!temp_is_copy(src)) {
-            temps[src].is_const = false;
             temps[src].is_copy = true;
             temps[src].next_copy = src;
             temps[src].prev_copy = src;
         }
-        temps[dst].is_const = false;
+        temps[dst].is_const = temps[src].is_const;
         temps[dst].is_copy = true;
+        temps[dst].val = temps[src].val;
         temps[dst].next_copy = temps[src].next_copy;
         temps[dst].prev_copy = src;
         temps[temps[dst].next_copy].prev_copy = dst;
-- 
2.1.4