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b20e0b1fdd
backend that they were all implemented except umul. This one fell back to the default implementation that did a hi/lo multiply and compared the top. Fix this to check the overflow flag that the 'mul' instruction sets, so we can avoid an explicit test. Now we compile: void *func(long count) { return new int[count]; } into: __Z4funcl: ## @_Z4funcl movl $4, %ecx ## encoding: [0xb9,0x04,0x00,0x00,0x00] movq %rdi, %rax ## encoding: [0x48,0x89,0xf8] mulq %rcx ## encoding: [0x48,0xf7,0xe1] seto %cl ## encoding: [0x0f,0x90,0xc1] testb %cl, %cl ## encoding: [0x84,0xc9] movq $-1, %rdi ## encoding: [0x48,0xc7,0xc7,0xff,0xff,0xff,0xff] cmoveq %rax, %rdi ## encoding: [0x48,0x0f,0x44,0xf8] jmp __Znam ## TAILCALL instead of: __Z4funcl: ## @_Z4funcl movl $4, %ecx ## encoding: [0xb9,0x04,0x00,0x00,0x00] movq %rdi, %rax ## encoding: [0x48,0x89,0xf8] mulq %rcx ## encoding: [0x48,0xf7,0xe1] testq %rdx, %rdx ## encoding: [0x48,0x85,0xd2] movq $-1, %rdi ## encoding: [0x48,0xc7,0xc7,0xff,0xff,0xff,0xff] cmoveq %rax, %rdi ## encoding: [0x48,0x0f,0x44,0xf8] jmp __Znam ## TAILCALL Other than the silly seto+test, this is using the o bit directly, so it's going in the right direction. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@120935 91177308-0d34-0410-b5e6-96231b3b80d8
15 lines
358 B
LLVM
15 lines
358 B
LLVM
; RUN: llc < %s -march=x86 | FileCheck %s
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declare {i32, i1} @llvm.umul.with.overflow.i32(i32 %a, i32 %b)
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define i1 @a(i32 %x) zeroext nounwind {
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%res = call {i32, i1} @llvm.umul.with.overflow.i32(i32 %x, i32 3)
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%obil = extractvalue {i32, i1} %res, 1
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ret i1 %obil
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; CHECK: a:
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; CHECK: mull
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; CHECK: seto %al
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; CHECK: movzbl %al, %eax
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; CHECK: ret
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}
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