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Diffstat (limited to 'gcc/testsuite/gcc.dg/pr42631.c')
-rw-r--r-- | gcc/testsuite/gcc.dg/pr42631.c | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/gcc/testsuite/gcc.dg/pr42631.c b/gcc/testsuite/gcc.dg/pr42631.c new file mode 100644 index 0000000..f5ac5a5 --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr42631.c @@ -0,0 +1,23 @@ +/* The function below expands to a loop whose latch block starts with + a PHI node and the corresponding debug stmt. In RTL, there are no + PHI nodes, but the debug insn that references the incoming k + remains, even though one of the incoming edges has it + uninitialized. After unrolling, however, the debug insn becomes + unconditional, and this exposed a problem in the webizer. Because + DF doesn't combine the uses of an uninitialized pseudo into a + single UD chain, we created a separate web for each use. + Allocating separate registers or stack slots for each uninitialized + use is wasteful, but the problem became more apparent in + -fcompare-debug tests: register numbers went out of sync, and could + have caused codegen differences depending on whether or not the + debug insns were present. The fix was to arrange for web to + combine uninitialized uses into a single web. */ + +/* { dg-do compile } */ +/* { dg-options "-g -O1 -funroll-loops -fcompare-debug" } */ + +void foo() +{ + unsigned k; + while (--k > 0); +} |