In a set of related phi-nodes and phi-sources if all phi-sources but one correspond to the target of one of the phi-sources, then no phi-nodes is needed and all %phis can be replaced by the unique source. For example, code like: int test(void); int foo(int a) { while (test()) a ^= 0; return a; } used to produce an IR with a phi-node for 'a', like: foo: phisrc.32 %phi2(a) <- %arg1 br .L4 .L4: phi.32 %r7(a) <- %phi2(a), %phi3(a) call.32 %r1 <- test cbr %r1, .L2, .L5 .L2: phisrc.32 %phi3(a) <- %r7(a) br .L4 .L5: ret.32 %r7(a) but since 'a ^= 0' is a no-op, the value of 'a' is in fact never mofified. This can be seen in the phi-node where its second operand (%phi3) is the same as its target (%r7). So the only possible value for 'a' is the one from the first operand, its initial value (%arg1). Once this trivial phi-nodes is removed, the IR is the expected: foo: br .L4 .L4: call.32 %r1 <- test cbr %r1, .L4, .L5 .L5: ret.32 %arg1 Removing these trivial phi-nodes will usually trigger other simplifications, especially those concerning the CFG. Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>