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https://github.com/c64scene-ar/llvm-6502.git
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9c2328e5a9
typedef struct { unsigned prefix : 4; unsigned code : 4; unsigned unsigned_p : 4; } tree_common;
int foo(tree_common *a, tree_common *b) { return a->code == b->code; }
into:
_foo:
movl 4(%esp), %eax
movl 8(%esp), %ecx
movl (%eax), %eax
xorl (%ecx), %eax
# TRUNCATE movb %al, %al
shrb $4, %al
testb %al, %al
sete %al
movzbl %al, %eax
ret
instead of:
_foo:
movl 8(%esp), %eax
movb (%eax), %al
shrb $4, %al
movl 4(%esp), %ecx
movb (%ecx), %cl
shrb $4, %cl
cmpb %al, %cl
sete %al
movzbl %al, %eax
ret
saving one cycle by eliminating a shift.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31727 91177308-0d34-0410-b5e6-96231b3b80d8
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