The linearization of nested logical expressions is not correct regarding the phi-nodes and their phi-sources. For example, code like: extern int a(void); int b(void); int c(void); static int foo(void) { return (a() && b()) && c(); } gives (optimized) IR like: foo: phisrc.32 %phi1 <- $0 call.32 %r1 <- a cbr %r1, .L4, .L3 .L4: call.32 %r3 <- b cbr %r3, .L2, .L3 .L2: call.32 %r5 <- c setne.32 %r7 <- %r5, $0 phisrc.32 %phi2 <- %r7 br .L3 .L3: phi.32 %r8 <- %phi2, %phi1 ret.32 %r8 The problem can already be seen by the fact that the phi-node in L3 has 2 operands while L3 has 3 parents. There is no phi-value for L4. The code is OK for non-nested logical expressions: linearize_cond_branch() takes the sucess/failure BB as argument, generate the code for those branches and there is a phi-node for each of them. However, with nested logical expressions, one of the BB will be shared between the inner and the outer expression. The phisrc will 'cover' one of the BB but only one of them. The solution is to add the phi-sources not before but after and add one for each of the parent BB. This way, it can be guaranteed that each parent BB has its phisrc, whatever the complexity of the sub- expressions. With this change, the generated IR becomes: foo: call.32 %r2 <- a phisrc.32 %phi1 <- $0 cbr %r2, .L4, .L3 .L4: call.32 %r4 <- b phisrc.32 %phi2 <- $0 cbr %r4, .L2, .L3 .L2: call.32 %r6 <- c setne.32 %r8 <- %r6, $0 phisrc.32 %phi3 <- %r8 br .L3 .L3: phi.32 %r1 <- %phi1, %phi2, %phi3 ret.32 %r1 Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>