X86 supports i8/i16 overflow ops (except i8 multiplies), we should
generate them.
Now we compile:
define zeroext i8 @X(i8 signext %a, i8 signext %b) nounwind ssp {
entry:
%0 = tail call %0 @llvm.sadd.with.overflow.i8(i8 %a, i8 %b)
%cmp = extractvalue %0 %0, 1
br i1 %cmp, label %if.then, label %if.end
into:
_X: ## @X
## BB#0: ## %entry
subl $12, %esp
movb 16(%esp), %al
addb 20(%esp), %al
jo LBB0_2
Before we were generating:
_X: ## @X
## BB#0: ## %entry
pushl %ebp
movl %esp, %ebp
subl $8, %esp
movb 12(%ebp), %al
testb %al, %al
setge %cl
movb 8(%ebp), %dl
testb %dl, %dl
setge %ah
cmpb %cl, %ah
sete %cl
addb %al, %dl
testb %dl, %dl
setge %al
cmpb %al, %ah
setne %al
andb %cl, %al
testb %al, %al
jne LBB0_2
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122186
91177308-0d34-0410-b5e6-
96231b3b80d8