[Qemu-devel] [PATCH v4 24/33] tcg-aarch64: Special case small constants in tcg_out_movi

[Richard Henderson]

Signed-off-by: Richard Henderson <address@hidden>
---
 tcg/aarch64/tcg-target.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/tcg/aarch64/tcg-target.c b/tcg/aarch64/tcg-target.c
index 9effee7..e50abcb 100644
--- a/tcg/aarch64/tcg-target.c
+++ b/tcg/aarch64/tcg-target.c
@@ -573,6 +573,17 @@ static void tcg_out_movi(TCGContext *s, TCGType type, 
TCGReg rd,
         type = TCG_TYPE_I32;
     }
 
+    /* Speed things up by handling the common case of small positive
+       and negative values specially.  */
+    if ((value & ~0xffffull) == 0) {
+        tcg_fmt_Rd_uimm(s, INSN_MOVZ, type, rd, value, 0);
+        return;
+    }
+    if ((~svalue & ~0xffffull) == 0) {
+        tcg_fmt_Rd_uimm(s, INSN_MOVN, type, rd, ~svalue, 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.
-- 
1.8.3.1