Patchwork [v4,24/33] tcg-aarch64: Special case small constants in tcg_out_movi

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Submitter Richard Henderson
Date Sept. 14, 2013, 9:54 p.m.
Message ID <1379195690-6509-25-git-send-email-rth@twiddle.net>
Download mbox | patch
Permalink /patch/274984/
State New
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Richard Henderson - Sept. 14, 2013, 9:54 p.m.
Signed-off-by: Richard Henderson <rth@twiddle.net>
---
 tcg/aarch64/tcg-target.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

Patch

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.