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	1. Only perform (zext (shl (zext x), y)) -> (shl (zext x), y) when y is a constant. This makes sure it remove at least one zest. 2. If the shift is a left shift, make sure the original shift cannot shift out bits. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91399 91177308-0d34-0410-b5e6-96231b3b80d8
		
			
				
	
	
		
			26 lines
		
	
	
		
			461 B
		
	
	
	
		
			LLVM
		
	
	
	
	
	
			
		
		
	
	
			26 lines
		
	
	
		
			461 B
		
	
	
	
		
			LLVM
		
	
	
	
	
	
| ; RUN: llc < %s -march=x86 | FileCheck %s
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| 
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| define i32 @t1(i8 zeroext %x) nounwind readnone ssp {
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| entry:
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| ; CHECK: t1:
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| ; CHECK: shll
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| ; CHECK-NOT: movzwl
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| ; CHECK: ret
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|   %0 = zext i8 %x to i16
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|   %1 = shl i16 %0, 5
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|   %2 = zext i16 %1 to i32
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|   ret i32 %2
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| }
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| 
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| define i32 @t2(i8 zeroext %x) nounwind readnone ssp {
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| entry:
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| ; CHECK: t2:
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| ; CHECK: shrl
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| ; CHECK-NOT: movzwl
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| ; CHECK: ret
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|   %0 = zext i8 %x to i16
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|   %1 = lshr i16 %0, 3
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|   %2 = zext i16 %1 to i32
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|   ret i32 %2
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| }
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