Which assembly mechanisms implement the various C control-flow constructs?

Question

Accepted Answer

Conditional jumps build if/loops, indirect jumps (through a jump table) build dense switches, and conditional moves build branch-free ?:.
Every high-level control structure boils down to just three machine-level techniques:

C construct
Assembly mechanism

if-then-else
cmp/test + conditional jump (jl, je, …)

do-while
cmp + conditional jump back to the body

while, for
Same as do-while, plus an initial guard test

switch (dense)
Indirect jump through a jump table — O(1)

switch (sparse)
Decision tree or if-else chain

ternary ?: (and simple ifs)
Conditional move (cmov) when it's safe to evaluate both sides

The unifying idea: assembly has no structured control flow. The compiler synthesizes all of it from comparisons and jumps. Standard rules of thumb worth memorizing: all loops become do-while, large switches become jump tables, and cheap branchless choices become cmov.
Go deeper:

Control flow (Wikipedia) — the whole control-flow picture in one place.

C construct	Assembly mechanism
`if`-`then`-`else`	`cmp`/`test` + conditional jump (`jl`, `je`, …)
`do`-`while`	`cmp` + conditional jump back to the body
`while`, `for`	Same as `do`-`while`, plus an initial guard test
`switch` (dense)	Indirect jump through a jump table — O(1)
`switch` (sparse)	Decision tree or if-else chain
ternary `?:` (and simple `if`s)	Conditional move (`cmov`) when it's safe to evaluate both sides