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111
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1 /* The function below expands to a loop whose latch block starts with
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2 a PHI node and the corresponding debug stmt. In RTL, there are no
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3 PHI nodes, but the debug insn that references the incoming k
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4 remains, even though one of the incoming edges has it
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5 uninitialized. After unrolling, however, the debug insn becomes
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6 unconditional, and this exposed a problem in the webizer. Because
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7 DF doesn't combine the uses of an uninitialized pseudo into a
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8 single UD chain, we created a separate web for each use.
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9 Allocating separate registers or stack slots for each uninitialized
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10 use is wasteful, but the problem became more apparent in
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11 -fcompare-debug tests: register numbers went out of sync, and could
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12 have caused codegen differences depending on whether or not the
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13 debug insns were present. The fix was to arrange for web to
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14 combine uninitialized uses into a single web. */
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15
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16 /* { dg-do compile } */
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17 /* { dg-options "-g -O1 -funroll-loops -fcompare-debug" } */
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18 /* { dg-xfail-if "" { powerpc-ibm-aix* } } */
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19
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20 void foo()
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21 {
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22 unsigned k;
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23 while (--k > 0);
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24 }
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