#DOWNLOAD MS VISUAL STUDIO PREVIEW 2017 DRIVER#
#DOWNLOAD MS VISUAL STUDIO PREVIEW 2017 MANUAL#
#DOWNLOAD MS VISUAL STUDIO PREVIEW 2017 CODE#

#DOWNLOAD MS VISUAL STUDIO PREVIEW 2017 DRIVER#

This topic contains information about versions of the Windows Driver Kit (WDK),Įnterprise WDK (EWDK), and additional downloads for support purposes. In small loops.The Windows Driver Kit (WDK) is used to develop, test, and deploy Windows Drivers. We missed an opportunity to use shifted MOVI/ MVNI for combining immediate move Ret Using MOVI/MVNI for immediate move in smaller loops

#DOWNLOAD MS VISUAL STUDIO PREVIEW 2017 CODE#

We have fixed this in Visual Studio 2022 17.8.2, and the code generation becomes: cmp w0, #0x11 Here, the compiler should have a better cost model and knows it will still be beneficial if it moves #32 into a register and employ CCMP’s register form. The immediate #32 does not fit into CCMP’s encoding, so the compiler will stop generating it, hence the code generation in Visual Studio 2022 17.7 was: cmp w0, #0x11īne w0, employs an if-then-else structure and is verbose. However, CCMP only takes a 5-bit immediate, so if we change the testcase to: int test (int a)

The CCMP (conditional compare) instruction is useful for accelerating short circuit evaluation, for example: int test (int a)įor this testcase, Visual Studio 2022 17.7 was smart enough to employ CCMP and generated: cmp w0, #0x11 Scalar code-generation now catches more CCMP opportunities

Therefore, the split is guided with use count. We only want to split the immediate when it has sole use site, otherwise we will end up with duplicated sequences. The immediate gets split in a way that the split parts fit into two AND instructions.

The code generation in Visual Studio 2022 17.8.2 is: and w8, w0, #0xFFFFC000 If we split 0x80004000 into 0xffffc000 and 0x80007fff, ANDing them sequentially will have the same effect as ANDing 0x80004000, but both 0xffffc000 and 0x80007fff fit into the rotated encoding, so we save one instruction. The code generation in Visual Studio 2022 17.7 was: mov w8, #0x4000 The compiler middle-end usually logically combines all the ANDed immediates with the return expression then returns a & 0x80004000 which does not fit into the rotated encoding, hence a MOV/ MOVK sequence will be generated to load the immediate, the cost will be three instructions. If one immediate does not fit into rotated encoding verbatim, it could after a split.įor example, programmers frequently write code patterns like the following: #define FLAG1_MASK 0x80000000

#DOWNLOAD MS VISUAL STUDIO PREVIEW 2017 MANUAL#

One improvement is: ARM64 has a rotated encoding for logic immediate (please refer to description of DecodeBitMasks in the Arm Architecture Reference Manual for details ), this immediate encoding is used by AND/ ORR. We have also taken steps further to improve immediate handling of other instructions. Scalar code-generation improved on logic immediate loading After the above-mentioned improvements, Visual Studio 2022 17.8.2 generates: |test_ge2gt| PROC There is an extra MOV instruction to materialize the immediate into the register because it does not fit into encoding verbatim. So, the code-generation is the following by Visual Studio 2022 17.7: |test_ge2gt| PROC However, if we subtract it by 1 and turn greater equal (ge) into greater (gt) accordingly, then 0x10000 will fit into the shifted encoding.įor test_lt2le, the negative immediate, -0x1fff, does not fit into immediate encoding for ARM64 CMN instruction, but if we subtract it by 1 and turn less (lt) into less equal (le) accordingly, then -0x2000 will fit into shifted encoding. Fromįor example: void test (double * _restrict a, unsigned long long * _restrict b)Ġx10001 inside test_ge2gt does not fit into the immediate encoding for the ARM64 CMP instruction, either verbatim or shifted. Now, they are all enabled in the ARM64 backend and hooked up with the auto-vectorizer. The following conversions between floating-point and integer types are common in real-world code. Auto-Vec torizer supports conversions between floating-point and integer Also, we have optimized instruction selection for a few scalar code-generation scenarios, for example short circuit evaluation, comparison against immediate, and smarter immediate split for logic instruction. In the last couple of months, we have been improving code-generation for the auto-vectorizer so that it can generate Neon instructions for more cases. While there is already a blog “ Visual Studio 17.8 now available!” covering new features and improvements, we would like to share more information with you about what is new for the MSVC ARM64 backend in this blog.

Visual Studio 2022 17.8 has been released recently (download it here).

Download ms visual studio preview 2017