[llvm-commits] [llvm] r47592 - in /llvm/trunk: lib/CodeGen/SimpleRegisterCoalescing.cpp test/CodeGen/X86/2008-02-25-X86-64-CoalescerBug.ll

[Christopher Lamb]

Hi Evan,

> +      // RAX: 0 -> AL, 1 -> AH, 2 -> AX, 3 -> EAX
> +      // EAX: 0 -> AL, 1 -> AH, 2 -> AX

The assumption that a subregister index refers to the same physical  
register across super register classes is target specific to X86 and  
not enforced in any way. If the target independent codegen will  
depend on this kind of relationship we should at least document it,  
but ideally it would either be explicit or enforced. Having this be  
magic is trouble waiting to happen...

--
Christopher Lamb

On Feb 26, 2008, at 12:03 AM, Evan Cheng wrote:

> Author: evancheng
> Date: Tue Feb 26 02:03:41 2008
> New Revision: 47592
>
> URL: http://llvm.org/viewvc/llvm-project?rev=47592&view=rev
> Log:
> This is possible:
> vr1 = extract_subreg vr2, 3
> ..
> vr3 = extract_subreg vr1, 2
> The end result is vr3 is equal to vr2 with subidx 2.
>
> Added:
>     llvm/trunk/test/CodeGen/X86/2008-02-25-X86-64-CoalescerBug.ll
> Modified:
>     llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.cpp
>
> Modified: llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/ 
> SimpleRegisterCoalescing.cpp?rev=47592&r1=47591&r2=47592&view=diff
>
> ====================================================================== 
> ========
> --- llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.cpp (original)
> +++ llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.cpp Tue Feb 26  
> 02:03:41 2008
> @@ -457,8 +457,14 @@
>        O.setSubReg(0);
>      } else {
>        unsigned OldSubIdx = O.getSubReg();
> -      assert((!SubIdx || !OldSubIdx) && "Conflicting sub-register  
> index!");
> -      if (SubIdx)
> +      // Sub-register indexes goes from small to large. e.g.
> +      // RAX: 0 -> AL, 1 -> AH, 2 -> AX, 3 -> EAX
> +      // EAX: 0 -> AL, 1 -> AH, 2 -> AX
> +      // So RAX's sub-register 2 is AX, RAX's sub-regsiter 3 is  
> EAX, whose
> +      // sub-register 2 is also AX.
> +      if (SubIdx && OldSubIdx && SubIdx != OldSubIdx)
> +        assert(OldSubIdx < SubIdx && "Conflicting sub-register  
> index!");
> +      else if (SubIdx)
>          O.setSubReg(SubIdx);
>        O.setReg(DstReg);
>      }
>
> Added: llvm/trunk/test/CodeGen/X86/2008-02-25-X86-64-CoalescerBug.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ 
> X86/2008-02-25-X86-64-CoalescerBug.ll?rev=47592&view=auto
>
> ====================================================================== 
> ========
> --- llvm/trunk/test/CodeGen/X86/2008-02-25-X86-64-CoalescerBug.ll  
> (added)
> +++ llvm/trunk/test/CodeGen/X86/2008-02-25-X86-64-CoalescerBug.ll  
> Tue Feb 26 02:03:41 2008
> @@ -0,0 +1,55 @@
> +; RUN: llvm-as < %s | llc -march=x86-64
> +
> +	%struct.XX = type <{ i8 }>
> +	%struct.YY = type { i64 }
> +	%struct.ZZ = type opaque
> +
> +define i8 @f(%struct.XX*** %fontMap, %struct.XX* %uen) signext  {
> +entry:
> +	%tmp45 = add i16 0, 1		; <i16> [#uses=2]
> +	br i1 false, label %bb124, label %bb53
> +
> +bb53:		; preds = %entry
> +	%tmp55 = call %struct.YY** @AA( i64 1, %struct.XX* %uen )		; <% 
> struct.YY**> [#uses=3]
> +	%tmp2728128 = load %struct.XX** null		; <%struct.XX*> [#uses=1]
> +	%tmp61 = load %struct.YY** %tmp55, align 8		; <%struct.YY*>  
> [#uses=1]
> +	%tmp62 = getelementptr %struct.YY* %tmp61, i32 0, i32 0		; <i64*>  
> [#uses=1]
> +	%tmp63 = load i64* %tmp62, align 8		; <i64> [#uses=1]
> +	%tmp6566 = zext i16 %tmp45 to i64		; <i64> [#uses=1]
> +	%tmp67 = shl i64 %tmp6566, 1		; <i64> [#uses=1]
> +	call void @BB( %struct.YY** %tmp55, i64 %tmp67, i8 signext  0, % 
> struct.XX* %uen )
> +	%tmp121131 = icmp eq i16 %tmp45, 1		; <i1> [#uses=1]
> +	br i1 %tmp121131, label %bb124, label %bb70.preheader
> +
> +bb70.preheader:		; preds = %bb53
> +	%tmp72 = bitcast %struct.XX* %tmp2728128 to %struct.ZZ***		; <% 
> struct.ZZ***> [#uses=1]
> +	br label %bb70
> +
> +bb70:		; preds = %bb119, %bb70.preheader
> +	%indvar133 = phi i32 [ %indvar.next134, %bb119 ], [ 0, % 
> bb70.preheader ]		; <i32> [#uses=2]
> +	%tmp.135 = trunc i64 %tmp63 to i32		; <i32> [#uses=1]
> +	%tmp136 = shl i32 %indvar133, 1		; <i32> [#uses=1]
> +	%DD = add i32 %tmp136, %tmp.135		; <i32> [#uses=1]
> +	%tmp73 = load %struct.ZZ*** %tmp72, align 8		; <%struct.ZZ**>  
> [#uses=0]
> +	br i1 false, label %bb119, label %bb77
> +
> +bb77:		; preds = %bb70
> +	%tmp8384 = trunc i32 %DD to i16		; <i16> [#uses=1]
> +	%tmp85 = sub i16 0, %tmp8384		; <i16> [#uses=1]
> +	store i16 %tmp85, i16* null, align 8
> +	call void @CC( %struct.YY** %tmp55, i64 0, i64 2, i8* null, % 
> struct.XX* %uen )
> +	ret i8 0
> +
> +bb119:		; preds = %bb70
> +	%indvar.next134 = add i32 %indvar133, 1		; <i32> [#uses=1]
> +	br label %bb70
> +
> +bb124:		; preds = %bb53, %entry
> +	ret i8 undef
> +}
> +
> +declare %struct.YY** @AA(i64, %struct.XX*)
> +
> +declare void @BB(%struct.YY**, i64, i8 signext , %struct.XX*)
> +
> +declare void @CC(%struct.YY**, i64, i64, i8*, %struct.XX*)
>
>
> _______________________________________________
> llvm-commits mailing list
> llvm-commits at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits

--
Christopher Lamb



-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20080308/4dc82f07/attachment.html>