RegsForValue::getCopyFromRegs doesn't know how to put an AssertSext on the
constructed BUILD_PAIR which represents the cast value.
+This can be handled by making CodeGenPrepare sink the cast.
+
//===---------------------------------------------------------------------===//
Test instructions can be eliminated by using EFLAGS values from arithmetic
0 is the only unsigned number < 1.
//===---------------------------------------------------------------------===//
+
+This code:
+
+%0 = type { i32, i1 }
+
+define i32 @add32carry(i32 %sum, i32 %x) nounwind readnone ssp {
+entry:
+ %uadd = tail call %0 @llvm.uadd.with.overflow.i32(i32 %sum, i32 %x)
+ %cmp = extractvalue %0 %uadd, 1
+ %inc = zext i1 %cmp to i32
+ %add = add i32 %x, %sum
+ %z.0 = add i32 %add, %inc
+ ret i32 %z.0
+}
+
+declare %0 @llvm.uadd.with.overflow.i32(i32, i32) nounwind readnone
+
+compiles to:
+
+_add32carry: ## @add32carry
+ addl %esi, %edi
+ sbbl %ecx, %ecx
+ movl %edi, %eax
+ subl %ecx, %eax
+ ret
+
+But it could be:
+
+_add32carry:
+ leal (%rsi,%rdi), %eax
+ cmpl %esi, %eax
+ adcl $0, %eax
+ ret
+
+//===---------------------------------------------------------------------===//