[Qemu-devel] [PATCH 06/26] tcg-aarch64: Special case small constants in tcg_out_movi

[Richard Henderson]

Signed-off-by: Richard Henderson <address@hidden>
---
 tcg/aarch64/tcg-target.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/tcg/aarch64/tcg-target.c b/tcg/aarch64/tcg-target.c
index 0f23e43..417f51a 100644
--- a/tcg/aarch64/tcg-target.c
+++ b/tcg/aarch64/tcg-target.c
@@ -577,6 +577,16 @@ static void tcg_out_movi(TCGContext *s, TCGType type, 
TCGReg rd,
     }
     ivalue = ~svalue;
 
+    /* Speed things up by handling the common case of small positive
+       and negative values specially.  */
+    if ((value & ~0xffffull) == 0) {
+        tcg_out_insn(s, 3405, MOVZ, type, rd, value, 0);
+        return;
+    } else if ((ivalue & ~0xffffull) == 0) {
+        tcg_out_insn(s, 3405, MOVN, type, rd, ivalue, 0);
+        return;
+    }
+
     /* Check for bitfield immediates.  For the benefit of 32-bit quantities,
        use the sign-extended value.  That lets us match rotated values such
        as 0xff0000ff with the same 64-bit logic matching 0xffffffffff0000ff. */
-- 
1.8.5.3