| Message ID | 20161117143507.3598-4-luc.vanoostenryck@gmail.com (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
diff --git a/simplify.c b/simplify.c index d07ca1b1..421b28f2 100644 --- a/simplify.c +++ b/simplify.c @@ -203,6 +203,7 @@ void kill_instruction(struct instruction *insn) return; case OP_PHI: + clear_phi(insn); insn->bb = NULL; repeat_phase |= REPEAT_CSE; return; diff --git a/validation/kill-phi-node.c b/validation/kill-phi-node.c new file mode 100644 index 00000000..88de9f96 --- /dev/null +++ b/validation/kill-phi-node.c @@ -0,0 +1,18 @@ +void foo(int a, int *b, unsigned int g); +void foo(int a, int *b, unsigned int g) +{ + int d = 0; + + if ((!a || *b) && g) + d = 16; + else + d = 8; +} + +/* + * check-name: kill-phi-node + * check-command: test-linearize $file + * + * check-output-ignore + * check-output-excludes: phisrc\\. + */
Currently kill_instruction() doesn't do anything with the sources of OP_PHI instructions. But when these instructions are removed the 'usage' of the associated sources must also be removed. This is not done and as result the instructions producing the phi-sources are not optimized away as expected. This patch fixes that by calling clear_phi() when killing a phi-instruction. For example, when looking at the output of test-linearize, the following function: void foo(int a, int *b, unsigned int g); void foo(int a, int *b, unsigned int g) { int d = 0; if ((!a || *b) && g) d = 16; else d = 8; } gives this output without the patch: foo: br %arg1, .L1, .L2 .L1: phisrc.32 %phi1 <- $1 br .L3 .L2: load.32 %r3 <- 0[%arg2] phisrc.32 %phi2 <- %r3 br .L3 .L3: ret The 'phisrc' instructions are obviously unneeded but nevertheless present. With the patch, the output is much closer to what's expected: foo: br %arg1, .L3, .L2 .L2: load.32 %r3 <- 0[%arg2] br .L3 .L3: ret Note 1) The 'load' instruction is also dead and should have been removed but it's separate problem. Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com> --- simplify.c | 1 + validation/kill-phi-node.c | 18 ++++++++++++++++++ 2 files changed, 19 insertions(+) create mode 100644 validation/kill-phi-node.c