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re PR target/36133 (GCC creates suboptimal ASM : Code includes unneeded TST instructions)
2008-11-19 Andrew Stubbs <ams@codesourcery.com> gcc/ PR target/36133 * config/m68k/m68k.h (CC_OVERFLOW_UNUSABLE, CC_NO_CARRY): New defines. * config/m68k/m68k.c (notice_update_cc): Set cc_status properly for shift instructions. * config/m68k/m68k.md: Adjust all conditional branches that use the carry and overflow flags so they understand CC_OVERFLOW_UNUSABLE. gcc/testsuite/ PR target/36133 * gcc.target/m68k/pr36133.c: New test. From-SVN: r141999
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Andrew Stubbs
Andrew Stubbs
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@ -1,3 +1,12 @@
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2008-11-19 Andrew Stubbs <ams@codesourcery.com>
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PR target/36133
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* config/m68k/m68k.h (CC_OVERFLOW_UNUSABLE, CC_NO_CARRY): New defines.
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* config/m68k/m68k.c (notice_update_cc): Set cc_status properly for
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shift instructions.
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* config/m68k/m68k.md: Adjust all conditional branches that use the
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carry and overflow flags so they understand CC_OVERFLOW_UNUSABLE.
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2008-11-18 Uros Bizjak <ubizjak@gmail.com>
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PR target/37362
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@ -3605,9 +3605,7 @@ notice_update_cc (rtx exp, rtx insn)
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case ROTATE: case ROTATERT:
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/* These instructions always clear the overflow bit, and set
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the carry to the bit shifted out. */
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/* ??? We don't currently have a way to signal carry not valid,
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nor do we check for it in the branch insns. */
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CC_STATUS_INIT;
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cc_status.flags |= CC_OVERFLOW_UNUSABLE | CC_NO_CARRY;
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break;
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case PLUS: case MINUS: case MULT:
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@ -855,6 +855,14 @@ __transfer_from_trampoline () \
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some or all of the saved cc's so they won't be used. */
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#define NOTICE_UPDATE_CC(EXP,INSN) notice_update_cc (EXP, INSN)
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/* The shift instructions always clear the overflow bit. */
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#define CC_OVERFLOW_UNUSABLE 01000
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/* The shift instructions use the carry bit in a way not compatible with
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conditional branches. conditions.h uses CC_NO_OVERFLOW for this purpose.
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Rename it to something more understandable. */
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#define CC_NO_CARRY CC_NO_OVERFLOW
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#define OUTPUT_JUMP(NORMAL, FLOAT, NO_OV) \
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do { if (cc_prev_status.flags & CC_IN_68881) \
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return FLOAT; \
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@ -6371,6 +6371,12 @@
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(pc)))]
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""
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{
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if ((cc_status.flags & CC_OVERFLOW_UNUSABLE) != 0)
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{
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cc_status.flags &= ~CC_OVERFLOW_UNUSABLE;
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return 0;
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}
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OUTPUT_JUMP ("jgt %l0", "fjgt %l0", 0);
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}
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[(set (attr "type") (symbol_ref "m68k_sched_branch_type (insn)"))])
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@ -6382,7 +6388,15 @@
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(label_ref (match_operand 0 "" ""))
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(pc)))]
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""
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"jhi %l0"
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{
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if ((cc_status.flags & CC_OVERFLOW_UNUSABLE) != 0)
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{
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cc_status.flags &= ~CC_OVERFLOW_UNUSABLE;
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return 0;
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}
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return "jhi %l0";
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}
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[(set_attr "type" "bcc")])
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(define_insn "blt"
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@ -6393,6 +6407,12 @@
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(pc)))]
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""
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{
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if ((cc_status.flags & CC_OVERFLOW_UNUSABLE) != 0)
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{
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cc_status.flags &= ~CC_OVERFLOW_UNUSABLE;
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return 0;
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}
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OUTPUT_JUMP ("jlt %l0", "fjlt %l0", "jmi %l0");
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}
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[(set (attr "type") (symbol_ref "m68k_sched_branch_type (insn)"))])
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@ -6404,7 +6424,15 @@
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(label_ref (match_operand 0 "" ""))
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(pc)))]
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""
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"jcs %l0"
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{
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if ((cc_status.flags & CC_OVERFLOW_UNUSABLE) != 0)
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{
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cc_status.flags &= ~CC_OVERFLOW_UNUSABLE;
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return 0;
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}
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return "jcs %l0";
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}
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[(set_attr "type" "bcc")])
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(define_insn "bge"
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@ -6415,6 +6443,12 @@
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(pc)))]
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""
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{
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if ((cc_status.flags & CC_OVERFLOW_UNUSABLE) != 0)
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{
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cc_status.flags &= ~CC_OVERFLOW_UNUSABLE;
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return 0;
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}
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OUTPUT_JUMP ("jge %l0", "fjge %l0", "jpl %l0");
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})
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@ -6425,7 +6459,15 @@
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(label_ref (match_operand 0 "" ""))
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(pc)))]
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""
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"jcc %l0"
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{
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if ((cc_status.flags & CC_OVERFLOW_UNUSABLE) != 0)
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{
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cc_status.flags &= ~CC_OVERFLOW_UNUSABLE;
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return 0;
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}
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return "jcc %l0";
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}
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[(set_attr "type" "bcc")])
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(define_insn "ble"
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@ -6436,6 +6478,12 @@
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(pc)))]
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""
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{
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if ((cc_status.flags & CC_OVERFLOW_UNUSABLE) != 0)
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{
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cc_status.flags &= ~CC_OVERFLOW_UNUSABLE;
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return 0;
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}
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OUTPUT_JUMP ("jle %l0", "fjle %l0", 0);
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}
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[(set_attr "type" "bcc")])
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@ -6447,7 +6495,15 @@
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(label_ref (match_operand 0 "" ""))
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(pc)))]
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""
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"jls %l0"
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{
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if ((cc_status.flags & CC_OVERFLOW_UNUSABLE) != 0)
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{
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cc_status.flags &= ~CC_OVERFLOW_UNUSABLE;
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return 0;
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}
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return "jls %l0";
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}
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[(set_attr "type" "bcc")])
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(define_insn "bordered"
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@ -6580,6 +6636,12 @@
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(label_ref (match_operand 0 "" ""))))]
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""
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{
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if ((cc_status.flags & CC_OVERFLOW_UNUSABLE) != 0)
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{
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cc_status.flags &= ~CC_OVERFLOW_UNUSABLE;
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return 0;
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}
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OUTPUT_JUMP ("jle %l0", "fjngt %l0", 0);
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}
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[(set_attr "type" "bcc")])
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@ -6591,7 +6653,15 @@
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(pc)
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(label_ref (match_operand 0 "" ""))))]
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""
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"jls %l0"
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{
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if ((cc_status.flags & CC_OVERFLOW_UNUSABLE) != 0)
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{
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cc_status.flags &= ~CC_OVERFLOW_UNUSABLE;
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return 0;
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}
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return "jls %l0";
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}
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[(set_attr "type" "bcc")])
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(define_insn "*blt_rev"
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@ -6602,6 +6672,12 @@
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(label_ref (match_operand 0 "" ""))))]
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""
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{
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if ((cc_status.flags & CC_OVERFLOW_UNUSABLE) != 0)
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{
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cc_status.flags &= ~CC_OVERFLOW_UNUSABLE;
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return 0;
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}
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OUTPUT_JUMP ("jge %l0", "fjnlt %l0", "jpl %l0");
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}
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[(set_attr "type" "bcc")])
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@ -6613,7 +6689,15 @@
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(pc)
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(label_ref (match_operand 0 "" ""))))]
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""
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"jcc %l0"
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{
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if ((cc_status.flags & CC_OVERFLOW_UNUSABLE) != 0)
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{
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cc_status.flags &= ~CC_OVERFLOW_UNUSABLE;
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return 0;
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}
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return "jcc %l0";
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}
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[(set_attr "type" "bcc")])
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(define_insn "*bge_rev"
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@ -6624,6 +6708,12 @@
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(label_ref (match_operand 0 "" ""))))]
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""
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{
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if ((cc_status.flags & CC_OVERFLOW_UNUSABLE) != 0)
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{
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cc_status.flags &= ~CC_OVERFLOW_UNUSABLE;
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return 0;
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}
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OUTPUT_JUMP ("jlt %l0", "fjnge %l0", "jmi %l0");
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}
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[(set_attr "type" "bcc")])
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@ -6635,7 +6725,15 @@
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(pc)
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(label_ref (match_operand 0 "" ""))))]
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""
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"jcs %l0"
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{
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if ((cc_status.flags & CC_OVERFLOW_UNUSABLE) != 0)
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{
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cc_status.flags &= ~CC_OVERFLOW_UNUSABLE;
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return 0;
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}
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return "jcs %l0";
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}
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[(set_attr "type" "bcc")])
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(define_insn "*ble_rev"
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@ -6646,6 +6744,12 @@
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(label_ref (match_operand 0 "" ""))))]
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""
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{
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if ((cc_status.flags & CC_OVERFLOW_UNUSABLE) != 0)
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{
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cc_status.flags &= ~CC_OVERFLOW_UNUSABLE;
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return 0;
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}
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OUTPUT_JUMP ("jgt %l0", "fjnle %l0", 0);
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}
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[(set_attr "type" "bcc")])
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@ -6657,7 +6761,15 @@
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(pc)
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(label_ref (match_operand 0 "" ""))))]
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""
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"jhi %l0"
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{
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if ((cc_status.flags & CC_OVERFLOW_UNUSABLE) != 0)
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{
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cc_status.flags &= ~CC_OVERFLOW_UNUSABLE;
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return 0;
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}
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return "jhi %l0";
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}
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[(set_attr "type" "bcc")])
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(define_insn "*bordered_rev"
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@ -1,3 +1,8 @@
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2008-11-19 Andrew Stubbs <ams@codesourcery.com>
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PR target/36133
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* gcc.target/m68k/pr36133.c: New test.
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2008-11-19 Maxim Kuvyrkov <maxim@codesourcery.com>
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* gcc.gd/struct/wo_prof_global_var.c: Use uninitialized integer
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16
gcc/testsuite/gcc.target/m68k/pr36133.c
Normal file
16
gcc/testsuite/gcc.target/m68k/pr36133.c
Normal file
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/* pr36133.c
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This test ensures that conditional branches can use the condition codes
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written by shift instructions, without the need for an extra TST. */
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/* { dg-do compile } */
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/* { dg-options "-O2" } */
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/* { dg-final { scan-assembler-not "tst" } } */
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void
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f (unsigned int a)
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{
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if (a >> 4)
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asm volatile ("nop");
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asm volatile ("nop");
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}
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