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| -rw-r--r-- | docs/LangRef.html | 49 |
1 files changed, 25 insertions, 24 deletions
diff --git a/docs/LangRef.html b/docs/LangRef.html index b4751e8189..fb1c768d8f 100644 --- a/docs/LangRef.html +++ b/docs/LangRef.html @@ -5119,43 +5119,44 @@ int *foo(struct ST *s) { } </pre> -<p>The LLVM code generated by the GCC frontend is:</p> +<p>The LLVM code generated by Clang is:</p> <pre class="doc_code"> -%RT = <a href="#namedtypes">type</a> { i8 , [10 x [20 x i32]], i8 } -%ST = <a href="#namedtypes">type</a> { i32, double, %RT } +%struct.RT = <a href="#namedtypes">type</a> { i8, [10 x [20 x i32]], i8 } +%struct.ST = <a href="#namedtypes">type</a> { i32, double, %struct.RT } -define i32* @foo(%ST* %s) { +define i32* @foo(%struct.ST* %s) nounwind uwtable readnone optsize ssp { entry: - %reg = getelementptr %ST* %s, i32 1, i32 2, i32 1, i32 5, i32 13 - ret i32* %reg + %arrayidx = getelementptr inbounds %struct.ST* %s, i64 1, i32 2, i32 1, i64 5, i64 13 + ret i32* %arrayidx } </pre> <h5>Semantics:</h5> -<p>In the example above, the first index is indexing into the '<tt>%ST*</tt>' - type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ i32, double, %RT - }</tt>' type, a structure. The second index indexes into the third element - of the structure, yielding a '<tt>%RT</tt>' = '<tt>{ i8 , [10 x [20 x i32]], - i8 }</tt>' type, another structure. The third index indexes into the second - element of the structure, yielding a '<tt>[10 x [20 x i32]]</tt>' type, an - array. The two dimensions of the array are subscripted into, yielding an - '<tt>i32</tt>' type. The '<tt>getelementptr</tt>' instruction returns a - pointer to this element, thus computing a value of '<tt>i32*</tt>' type.</p> +<p>In the example above, the first index is indexing into the + '<tt>%struct.ST*</tt>' type, which is a pointer, yielding a + '<tt>%struct.ST</tt>' = '<tt>{ i32, double, %struct.RT }</tt>' type, a + structure. The second index indexes into the third element of the structure, + yielding a '<tt>%struct.RT</tt>' = '<tt>{ i8 , [10 x [20 x i32]], i8 }</tt>' + type, another structure. The third index indexes into the second element of + the structure, yielding a '<tt>[10 x [20 x i32]]</tt>' type, an array. The + two dimensions of the array are subscripted into, yielding an '<tt>i32</tt>' + type. The '<tt>getelementptr</tt>' instruction returns a pointer to this + element, thus computing a value of '<tt>i32*</tt>' type.</p> <p>Note that it is perfectly legal to index partially through a structure, returning a pointer to an inner element. Because of this, the LLVM code for the given testcase is equivalent to:</p> -<pre> - define i32* @foo(%ST* %s) { - %t1 = getelementptr %ST* %s, i32 1 <i>; yields %ST*:%t1</i> - %t2 = getelementptr %ST* %t1, i32 0, i32 2 <i>; yields %RT*:%t2</i> - %t3 = getelementptr %RT* %t2, i32 0, i32 1 <i>; yields [10 x [20 x i32]]*:%t3</i> - %t4 = getelementptr [10 x [20 x i32]]* %t3, i32 0, i32 5 <i>; yields [20 x i32]*:%t4</i> - %t5 = getelementptr [20 x i32]* %t4, i32 0, i32 13 <i>; yields i32*:%t5</i> - ret i32* %t5 - } +<pre class="doc_code"> +define i32* @foo(%struct.ST* %s) { + %t1 = getelementptr %struct.ST* %s, i32 1 <i>; yields %struct.ST*:%t1</i> + %t2 = getelementptr %struct.ST* %t1, i32 0, i32 2 <i>; yields %struct.RT*:%t2</i> + %t3 = getelementptr %struct.RT* %t2, i32 0, i32 1 <i>; yields [10 x [20 x i32]]*:%t3</i> + %t4 = getelementptr [10 x [20 x i32]]* %t3, i32 0, i32 5 <i>; yields [20 x i32]*:%t4</i> + %t5 = getelementptr [20 x i32]* %t4, i32 0, i32 13 <i>; yields i32*:%t5</i> + ret i32* %t5 +} </pre> <p>If the <tt>inbounds</tt> keyword is present, the result value of the |