allocation magic to make the hack go away (e.g. putting additional constraints
on the result of the movb).
+//===---------------------------------------------------------------------===//
+
+This function:
+double a(double b) {return (unsigned)b;}
+compiles to this code:
+
+_a:
+ subq $8, %rsp
+ cvttsd2siq %xmm0, %rax
+ movl $4294967295, %ecx
+ andq %rcx, %rax
+ cvtsi2sdq %rax, %xmm0
+ addq $8, %rsp
+ ret
+
+note the dead rsp adjustments. Also, there is surely a better/shorter way
+to clear the top 32-bits of a 64-bit register than movl+andq. Testcase here:
+
+unsigned long long c(unsigned long long a) {return a&4294967295; }
+
+_c:
+ movl $4294967295, %ecx
+ movq %rdi, %rax
+ andq %rcx, %rax
+ ret
+
+//===---------------------------------------------------------------------===//