From: Richard Henderson <rth@twiddle.net>
Date: Wed, 27 Mar 2013 18:37:42 +0000 (-0400)
Subject: tcg-s390: Use all 20 bits of the offset in tcg_out_mem
X-Git-Tag: v1.5.0-rc0~311^2~1
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=78c9f7c5b09408b4cac69a4fee97a118c8a89f6c;p=thirdparty%2Fqemu.git

tcg-s390: Use all 20 bits of the offset in tcg_out_mem

This can save one insn, if the constant has any bits in 32-63 set,
but no bits in 21-31 set.  It never results in more insns.

Signed-off-by: Richard Henderson <rth@twiddle.net>
---

diff --git a/tcg/s390/tcg-target.c b/tcg/s390/tcg-target.c
index 22927dfa262..8e660b318da 100644
--- a/tcg/s390/tcg-target.c
+++ b/tcg/s390/tcg-target.c
@@ -748,10 +748,11 @@ static void tcg_out_mem(TCGContext *s, S390Opcode opc_rx, S390Opcode opc_rxy,
                         tcg_target_long ofs)
 {
     if (ofs < -0x80000 || ofs >= 0x80000) {
-        /* Combine the low 16 bits of the offset with the actual load insn;
-           the high 48 bits must come from an immediate load.  */
-        tcg_out_movi(s, TCG_TYPE_PTR, TCG_TMP0, ofs & ~0xffff);
-        ofs &= 0xffff;
+        /* Combine the low 20 bits of the offset with the actual load insn;
+           the high 44 bits must come from an immediate load.  */
+        tcg_target_long low = ((ofs & 0xfffff) ^ 0x80000) - 0x80000;
+        tcg_out_movi(s, TCG_TYPE_PTR, TCG_TMP0, ofs - low);
+        ofs = low;
 
         /* If we were already given an index register, add it in.  */
         if (index != TCG_REG_NONE) {