[cfe-commits] implicit sign/bitwidth conversions during array indexing?

[Ted Kremenek]

Okay.  Then Sema should insert an ImplicitCastExpr, just like it does  
for x1 and x2.

On Nov 13, 2008, at 8:24 PM, Zhongxing Xu wrote:

>
> I'm not certain.  Note that the 'long long' value 'k' was not  
> truncated.  Is this a Sema bug, or is this the correct behavior?   
> For this target LongLongWidth is 64, the bit width for 'int' is 32,  
> and the bit width for a pointer is (I believe) 32 bits as well.
>
> It's truncated in the generated code:
>
> void f() {
>   int a[10];
>   short x1;
>   unsigned short x2;
>   long x5;
>   unsigned long x6;
>   long long x3;
>   unsigned long long x4;
>
>   a[x1] = 3;
>   a[x2] = 3;
>   a[x3] = 3;
>   a[x4] = 3;
>   a[x5] = 3;
>   a[x6] = 3;
> }
>
> ; ModuleID = 'array3.c'
> target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32- 
> i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64- 
> f80:32:32"
> target triple = "i686-pc-linux-gnu"
>
> define void @f(...) nounwind {
> entry:
>     %a = alloca [10 x i32], align 4        ; <[10 x i32]*> [#uses=6]
>     %x1 = alloca i16, align 2        ; <i16*> [#uses=1]
>     %x2 = alloca i16, align 2        ; <i16*> [#uses=1]
>     %x5 = alloca i32, align 4        ; <i32*> [#uses=1]
>     %x6 = alloca i32, align 4        ; <i32*> [#uses=1]
>     %x3 = alloca i64, align 4        ; <i64*> [#uses=1]
>     %x4 = alloca i64, align 4        ; <i64*> [#uses=1]
>     %tmp = load i16* %x1        ; <i16> [#uses=1]
>     %arraydecay = getelementptr [10 x i32]* %a, i32 0, i32  
> 0        ; <i32*> [#uses=1]
>     %idxprom = sext i16 %tmp to i32        ; <i32> [#uses=1]
>     %arrayidx = getelementptr i32* %arraydecay, i32  
> %idxprom        ; <i32*> [#uses=1]
>     store i32 3, i32* %arrayidx
>     %tmp1 = load i16* %x2        ; <i16> [#uses=1]
>     %arraydecay2 = getelementptr [10 x i32]* %a, i32 0, i32  
> 0        ; <i32*> [#uses=1]
>     %idxprom3 = zext i16 %tmp1 to i32        ; <i32> [#uses=1]
>     %arrayidx4 = getelementptr i32* %arraydecay2, i32  
> %idxprom3        ; <i32*> [#uses=1]
>     store i32 3, i32* %arrayidx4
>     %tmp5 = load i64* %x3        ; <i64> [#uses=1]
>     %arraydecay6 = getelementptr [10 x i32]* %a, i32 0, i32  
> 0        ; <i32*> [#uses=1]
>     %idxprom7 = trunc i64 %tmp5 to i32        ; <i32> [#uses=1]
>     %arrayidx8 = getelementptr i32* %arraydecay6, i32  
> %idxprom7        ; <i32*> [#uses=1]
>     store i32 3, i32* %arrayidx8
>     %tmp9 = load i64* %x4        ; <i64> [#uses=1]
>     %arraydecay10 = getelementptr [10 x i32]* %a, i32 0, i32  
> 0        ; <i32*> [#uses=1]
>     %idxprom11 = trunc i64 %tmp9 to i32        ; <i32> [#uses=1]
>     %arrayidx12 = getelementptr i32* %arraydecay10, i32  
> %idxprom11        ; <i32*> [#uses=1]
>     store i32 3, i32* %arrayidx12
>     %tmp13 = load i32* %x5        ; <i32> [#uses=1]
>     %arraydecay14 = getelementptr [10 x i32]* %a, i32 0, i32  
> 0        ; <i32*> [#uses=1]
>     %arrayidx15 = getelementptr i32* %arraydecay14, i32  
> %tmp13        ; <i32*> [#uses=1]
>     store i32 3, i32* %arrayidx15
>     %tmp16 = load i32* %x6        ; <i32> [#uses=1]
>     %arraydecay17 = getelementptr [10 x i32]* %a, i32 0, i32  
> 0        ; <i32*> [#uses=1]
>     %arrayidx18 = getelementptr i32* %arraydecay17, i32  
> %tmp16        ; <i32*> [#uses=1]
>     store i32 3, i32* %arrayidx18
>     br label %return
>
> return:        ; preds = %entry
>     ret void
> }

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