[IR] Make {extract,insert}element accept an index of any integer type.

Given the following C code llvm currently generates suboptimal code for
x86-64:

__m128 bss4( const __m128 *ptr, size_t i, size_t j )
{
    float f = ptr[i][j];
    return (__m128) { f, f, f, f };
}

=================================================

define <4 x float> @_Z4bss4PKDv4_fmm(<4 x float>* nocapture readonly %ptr, i64 %i, i64 %j) #0 {
  %a1 = getelementptr inbounds <4 x float>* %ptr, i64 %i
  %a2 = load <4 x float>* %a1, align 16, !tbaa !1
  %a3 = trunc i64 %j to i32
  %a4 = extractelement <4 x float> %a2, i32 %a3
  %a5 = insertelement <4 x float> undef, float %a4, i32 0
  %a6 = insertelement <4 x float> %a5, float %a4, i32 1
  %a7 = insertelement <4 x float> %a6, float %a4, i32 2
  %a8 = insertelement <4 x float> %a7, float %a4, i32 3
  ret <4 x float> %a8
}

=================================================

        shlq    $4, %rsi
        addq    %rdi, %rsi
        movslq  %edx, %rax
        vbroadcastss    (%rsi,%rax,4), %xmm0
        retq

=================================================

The movslq is uneeded, but is present because of the trunc to i32 and then
sext back to i64 that the backend adds for vbroadcastss.

We can't remove it because it changes the meaning. The IR that clang
generates is already suboptimal. What clang really should emit is:

  %a4 = extractelement <4 x float> %a2, i64 %j

This patch makes that legal. A separate patch will teach clang to do it.

Differential Revision: http://reviews.llvm.org/D3519

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207801 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 4 insertions, 4 deletions

diff --git a/docs/LangRef.rst b/docs/LangRef.rst
index a6595f7fd0..3d99a0e79b 100644
--- a/docs/LangRef.rst
+++ b/docs/LangRef.rst
@@ -4470,7 +4470,7 @@ Syntax:
 
 ::
 
-      <result> = extractelement <n x <ty>> <val>, i32 <idx>    ; yields <ty>
+      <result> = extractelement <n x <ty>> <val>, <ty2> <idx>  ; yields <ty>
 
 Overview:
 """""""""
@@ -4484,7 +4484,7 @@ Arguments:
 The first operand of an '``extractelement``' instruction is a value of
 :ref:`vector <t_vector>` type. The second operand is an index indicating
 the position from which to extract the element. The index may be a
-variable.
+variable of any integer type.
 
 Semantics:
 """"""""""
@@ -4510,7 +4510,7 @@ Syntax:
 
 ::
 
-      <result> = insertelement <n x <ty>> <val>, <ty> <elt>, i32 <idx>    ; yields <n x <ty>>
+      <result> = insertelement <n x <ty>> <val>, <ty> <elt>, <ty2> <idx>    ; yields <n x <ty>>
 
 Overview:
 """""""""
@@ -4525,7 +4525,7 @@ The first operand of an '``insertelement``' instruction is a value of
 :ref:`vector <t_vector>` type. The second operand is a scalar value whose
 type must equal the element type of the first operand. The third operand
 is an index indicating the position at which to insert the value. The
-index may be a variable.
+index may be a variable of any integer type.
 
 Semantics:
 """"""""""