llvm-mirror/bit-test-shift.ll at e5ccfcac27cc9d6682526c28a6abf6bf7081729b - llvm-mirror - Git.je (Gitea)

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Owen Anderson 7d6373ea9d A select between a constant and zero, when fed by a bit test, can be efficiently

lowered using a series of shifts.
Fixes <rdar://problem/8285015>.

llvm-svn: 114599

2010-09-22 22:58:22 +00:00

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 ; RUN: llc < %s -march=x86 | FileCheck %s
 ; <rdar://problem/8285015>
 define i32 @x(i32 %t) nounwind readnone ssp {
 entry:
 ; CHECK: shll	$23, %eax
 ; CHECK: sarl	$31, %eax
 ; CHECK: andl	$-26, %eax
   %and = and i32 %t, 256
   %tobool = icmp eq i32 %and, 0
   %retval.0 = select i1 %tobool, i32 0, i32 -26
   ret i32 %retval.0
 }