X86: Add a bunch of peeps for add and sub of SETB.
"b + ((a < b) ? 1 : 0)" compiles into
cmpl %esi, %edi
adcl $0, %esi
instead of
cmpl %esi, %edi
sbbl %eax, %eax
andl $1, %eax
addl %esi, %eax
This saves a register, a false dependency on %eax
(Intel's CPUs still don't ignore it) and it's shorter.
llvm-svn: 131070
diff --git a/llvm/lib/Target/X86/X86InstrCompiler.td b/llvm/lib/Target/X86/X86InstrCompiler.td
index 4c915d9..b28cd83 100644
--- a/llvm/lib/Target/X86/X86InstrCompiler.td
+++ b/llvm/lib/Target/X86/X86InstrCompiler.td
@@ -214,6 +214,30 @@
def : Pat<(and (i8 (X86setcc_c X86_COND_B, EFLAGS)), 1),
(SETBr)>;
+// (add OP, SETB) -> (adc OP, 0)
+def : Pat<(add (and (i8 (X86setcc_c X86_COND_B, EFLAGS)), 1), GR8:$op),
+ (ADC8ri GR8:$op, 0)>;
+def : Pat<(add (and (i32 (X86setcc_c X86_COND_B, EFLAGS)), 1), GR32:$op),
+ (ADC32ri8 GR32:$op, 0)>;
+def : Pat<(add (and (i64 (X86setcc_c X86_COND_B, EFLAGS)), 1), GR64:$op),
+ (ADC64ri8 GR64:$op, 0)>;
+
+// (sub OP, SETB) -> (sbb OP, 0)
+def : Pat<(sub GR8:$op, (and (i8 (X86setcc_c X86_COND_B, EFLAGS)), 1)),
+ (SBB8ri GR8:$op, 0)>;
+def : Pat<(sub GR32:$op, (and (i32 (X86setcc_c X86_COND_B, EFLAGS)), 1)),
+ (SBB32ri8 GR32:$op, 0)>;
+def : Pat<(sub GR64:$op, (and (i64 (X86setcc_c X86_COND_B, EFLAGS)), 1)),
+ (SBB64ri8 GR64:$op, 0)>;
+
+// (sub OP, SETCC_CARRY) -> (adc OP, 0)
+def : Pat<(sub GR8:$op, (i8 (X86setcc_c X86_COND_B, EFLAGS))),
+ (ADC8ri GR8:$op, 0)>;
+def : Pat<(sub GR32:$op, (i32 (X86setcc_c X86_COND_B, EFLAGS))),
+ (ADC32ri8 GR32:$op, 0)>;
+def : Pat<(sub GR64:$op, (i64 (X86setcc_c X86_COND_B, EFLAGS))),
+ (ADC64ri8 GR64:$op, 0)>;
+
//===----------------------------------------------------------------------===//
// String Pseudo Instructions
//