65 lines
2.0 KiB
Diff
65 lines
2.0 KiB
Diff
2015-02-26 Jakub Jelinek <jakub@redhat.com>
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Aldy Hernandez <aldyh@redhat.com>
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PR rtl-optimization/65220
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* config/i386/i386.md (*udivmod<mode>4_pow2): New.
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--- gcc/config/i386/i386.md (revision 221063)
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+++ gcc/config/i386/i386.md (revision 221064)
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@@ -7331,6 +7331,32 @@ (define_insn_and_split "*udivmod<mode>4"
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[(set_attr "type" "multi")
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(set_attr "mode" "<MODE>")])
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+;; Optimize division or modulo by constant power of 2, if the constant
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+;; materializes only after expansion.
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+(define_insn_and_split "*udivmod<mode>4_pow2"
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+ [(set (match_operand:SWI48 0 "register_operand" "=r")
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+ (udiv:SWI48 (match_operand:SWI48 2 "register_operand" "0")
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+ (match_operand:SWI48 3 "const_int_operand" "n")))
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+ (set (match_operand:SWI48 1 "register_operand" "=r")
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+ (umod:SWI48 (match_dup 2) (match_dup 3)))
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+ (clobber (reg:CC FLAGS_REG))]
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+ "UINTVAL (operands[3]) - 2 < <MODE_SIZE> * BITS_PER_UNIT
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+ && (UINTVAL (operands[3]) & (UINTVAL (operands[3]) - 1)) == 0"
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+ "#"
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+ "&& reload_completed"
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+ [(set (match_dup 1) (match_dup 2))
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+ (parallel [(set (match_dup 0) (lshiftrt:<MODE> (match_dup 2) (match_dup 4)))
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+ (clobber (reg:CC FLAGS_REG))])
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+ (parallel [(set (match_dup 1) (and:<MODE> (match_dup 1) (match_dup 5)))
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+ (clobber (reg:CC FLAGS_REG))])]
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+{
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+ int v = exact_log2 (UINTVAL (operands[3]));
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+ operands[4] = GEN_INT (v);
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+ operands[5] = GEN_INT ((HOST_WIDE_INT_1U << v) - 1);
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+}
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+ [(set_attr "type" "multi")
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+ (set_attr "mode" "<MODE>")])
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+
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(define_insn "*udivmod<mode>4_noext"
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[(set (match_operand:SWIM248 0 "register_operand" "=a")
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(udiv:SWIM248 (match_operand:SWIM248 2 "register_operand" "0")
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--- gcc/testsuite/gcc.target/i386/pr65520.c (revision 0)
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+++ gcc/testsuite/gcc.target/i386/pr65520.c (revision 221064)
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@@ -0,0 +1,20 @@
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+/* PR target/65520 */
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+/* { dg-do compile } */
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+/* { dg-options "-O2" } */
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+
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+int foo (void *);
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+
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+void
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+bar (void)
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+{
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+ unsigned s = 128;
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+ while (1)
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+ {
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+ unsigned b[s];
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+ if (foo (b))
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+ break;
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+ s *= 2;
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+ }
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+}
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+
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+/* { dg-final { scan-assembler-not "div\[^\n\r]*%" } } */
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