X86: Use btq for bit tests if the immediate can't be encoded in 32 bits.
Before:
movabsq $4294967296, %rax ## encoding: [0x48,0xb8,0x00,0x00,0x00,0x00,0x01,0x00,0x00,0x00]
testq %rax, %rdi ## encoding: [0x48,0x85,0xf8]
jne LBB0_2 ## encoding: [0x75,A]
After:
btq $32, %rdi ## encoding: [0x48,0x0f,0xba,0xe7,0x20]
jb LBB0_2 ## encoding: [0x72,A]
btq is usually slower than testq because it doesn't fuse with the jump, but here we're better off
saving one register and a giant movabsq.
llvm-svn: 145103
2011-11-23 14:54:17 +01:00
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; RUN: llc < %s -march=x86-64 | FileCheck %s
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declare void @bar()
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define void @test1(i64 %foo) nounwind {
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%and = and i64 %foo, 4294967296
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%tobool = icmp eq i64 %and, 0
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br i1 %tobool, label %if.end, label %if.then
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2013-07-13 22:38:47 +02:00
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; CHECK-LABEL: test1:
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X86: Use btq for bit tests if the immediate can't be encoded in 32 bits.
Before:
movabsq $4294967296, %rax ## encoding: [0x48,0xb8,0x00,0x00,0x00,0x00,0x01,0x00,0x00,0x00]
testq %rax, %rdi ## encoding: [0x48,0x85,0xf8]
jne LBB0_2 ## encoding: [0x75,A]
After:
btq $32, %rdi ## encoding: [0x48,0x0f,0xba,0xe7,0x20]
jb LBB0_2 ## encoding: [0x72,A]
btq is usually slower than testq because it doesn't fuse with the jump, but here we're better off
saving one register and a giant movabsq.
llvm-svn: 145103
2011-11-23 14:54:17 +01:00
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; CHECK: btq $32
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if.then:
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tail call void @bar() nounwind
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br label %if.end
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if.end:
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ret void
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}
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define void @test2(i64 %foo) nounwind {
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%and = and i64 %foo, 2147483648
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%tobool = icmp eq i64 %and, 0
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br i1 %tobool, label %if.end, label %if.then
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2013-07-13 22:38:47 +02:00
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; CHECK-LABEL: test2:
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X86: Use btq for bit tests if the immediate can't be encoded in 32 bits.
Before:
movabsq $4294967296, %rax ## encoding: [0x48,0xb8,0x00,0x00,0x00,0x00,0x01,0x00,0x00,0x00]
testq %rax, %rdi ## encoding: [0x48,0x85,0xf8]
jne LBB0_2 ## encoding: [0x75,A]
After:
btq $32, %rdi ## encoding: [0x48,0x0f,0xba,0xe7,0x20]
jb LBB0_2 ## encoding: [0x72,A]
btq is usually slower than testq because it doesn't fuse with the jump, but here we're better off
saving one register and a giant movabsq.
llvm-svn: 145103
2011-11-23 14:54:17 +01:00
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; CHECK: testl $-2147483648
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if.then:
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tail call void @bar() nounwind
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br label %if.end
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if.end:
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ret void
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}
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