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We lower setb to sbb with the hope that the and will go away, when it
doesn't, match it back to setb. On a 64-bit version of the testcase before we'd get: movq %rdi, %rax addq %rsi, %rax sbbb %dl, %dl andb $1, %dl ret now we get: movq %rdi, %rax addq %rsi, %rax setb %dl ret git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122217 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -207,6 +207,12 @@ def : Pat<(i32 (sext (i8 (X86setcc_c X86_COND_B, EFLAGS)))),
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def : Pat<(i64 (sext (i8 (X86setcc_c X86_COND_B, EFLAGS)))),
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(SETB_C64r)>;
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// We canonicalize 'setb' to "(and (sbb reg,reg), 1)" on the hope that the and
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// will be eliminated and that the sbb can be extended up to a wider type. When
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// this happens, it is great. However, if we are left with an 8-bit sbb and an
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// and, we might as well just match it as a setb.
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def : Pat<(and (i8 (X86setcc_c X86_COND_B, EFLAGS)), 1),
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(SETBr)>;
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//===----------------------------------------------------------------------===//
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// String Pseudo Instructions
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@ -92,3 +92,12 @@ define i64 @test6(i64 %A, i32 %B) nounwind {
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; X64: ret
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}
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define {i32, i1} @test7(i32 %v1, i32 %v2) nounwind {
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%t = call {i32, i1} @llvm.uadd.with.overflow.i32(i32 %v1, i32 %v2)
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ret {i32, i1} %t
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}
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; X64: test7:
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; X64: addl %esi, %eax
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; X64-NEXT: setb %dl
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; X64-NEXT: ret
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