[Qemu-devel] [PATCH 04/19] tcg-ia64: Simplify brcond

[Richard Henderson <rth@twiddle.net>]

There was a misconception that a stop bit is required between a compare
and the branch that uses the predicate set by the compare.  This lead to
the usage of an extra bundle in which to perform the compare.  The extra
bundle left room for constants to be loaded for use with the compare insn.

If we pack the compare and the branch together in the same bundle, then
there's no longer any room for non-zero constants.  At which point we
can eliminate half the function by not handling them.

Signed-off-by: Richard Henderson <rth@twiddle.net>
---
 tcg/ia64/tcg-target.c | 42 +++++++++---------------------------------
 1 file changed, 9 insertions(+), 33 deletions(-)

diff --git a/tcg/ia64/tcg-target.c b/tcg/ia64/tcg-target.c
index 6708844..413e00f 100644
--- a/tcg/ia64/tcg-target.c
+++ b/tcg/ia64/tcg-target.c
@@ -1442,38 +1442,16 @@ static inline uint64_t tcg_opc_cmp_a(int qp, TCGCond cond, TCGArg arg1,
     }
 }
 
-static inline void tcg_out_brcond(TCGContext *s, TCGCond cond, TCGArg arg1,
-                                  int const_arg1, TCGArg arg2, int const_arg2,
-                                  int label_index, int cmp4)
+static inline void tcg_out_brcond(TCGContext *s, TCGCond cond, TCGReg arg1,
+                                  TCGReg arg2, int label_index, int cmp4)
 {
     TCGLabel *l = &s->labels[label_index];
-    uint64_t opc1, opc2;
 
-    if (const_arg1 && arg1 != 0) {
-        opc1 = tcg_opc_a5(TCG_REG_P0, OPC_ADDL_A5, TCG_REG_R2,
-                          arg1, TCG_REG_R0);
-        arg1 = TCG_REG_R2;
-    } else {
-        opc1 = INSN_NOP_M;
-    }
-
-    if (const_arg2 && arg2 != 0) {
-        opc2 = tcg_opc_a5(TCG_REG_P0, OPC_ADDL_A5, TCG_REG_R3,
-                          arg2, TCG_REG_R0);
-        arg2 = TCG_REG_R3;
-    } else {
-        opc2 = INSN_NOP_I;
-    }
-
-    tcg_out_bundle(s, mII,
-                   opc1,
-                   opc2,
-                   tcg_opc_cmp_a(TCG_REG_P0, cond, arg1, arg2, cmp4));
-    tcg_out_bundle(s, mmB,
-                   INSN_NOP_M,
+    tcg_out_bundle(s, miB,
                    INSN_NOP_M,
-                   tcg_opc_b1 (TCG_REG_P6, OPC_BR_DPTK_FEW_B1,
-                               get_reloc_pcrel21b(s->code_ptr + 2)));
+                   tcg_opc_cmp_a(TCG_REG_P0, cond, arg1, arg2, cmp4),
+                   tcg_opc_b1(TCG_REG_P6, OPC_BR_DPTK_FEW_B1,
+                              get_reloc_pcrel21b(s->code_ptr + 2)));
 
     if (l->has_value) {
         reloc_pcrel21b((s->code_ptr - 16) + 2, l->u.value);
@@ -2222,12 +2200,10 @@ static inline void tcg_out_op(TCGContext *s, TCGOpcode opc,
         break;
 
     case INDEX_op_brcond_i32:
-        tcg_out_brcond(s, args[2], args[0], const_args[0],
-                       args[1], const_args[1], args[3], 1);
+        tcg_out_brcond(s, args[2], args[0], args[1], args[3], 1);
         break;
     case INDEX_op_brcond_i64:
-        tcg_out_brcond(s, args[2], args[0], const_args[0],
-                       args[1], const_args[1], args[3], 0);
+        tcg_out_brcond(s, args[2], args[0], args[1], args[3], 0);
         break;
     case INDEX_op_setcond_i32:
         tcg_out_setcond(s, args[3], args[0], args[1], args[2], 1);
@@ -2331,7 +2307,7 @@ static const TCGTargetOpDef ia64_op_defs[] = {
     { INDEX_op_bswap16_i32, { "r", "rZ" } },
     { INDEX_op_bswap32_i32, { "r", "rZ" } },
 
-    { INDEX_op_brcond_i32, { "rI", "rI" } },
+    { INDEX_op_brcond_i32, { "rZ", "rZ" } },
     { INDEX_op_setcond_i32, { "r", "rZ", "rZ" } },
     { INDEX_op_movcond_i32, { "r", "rZ", "rZ", "rI", "rI" } },
 
-- 
1.8.3.1