From 2e415e7239cc2942c838694642c54326e84e86bc Mon Sep 17 00:00:00 2001 From: TimothyLottes Date: Sat, 12 Nov 2016 23:15:08 -0500 Subject: [PATCH] Add files via upload --- 20101004.html | 10 ++++++++++ 20101005.html | 9 +++++++++ index.html | 5 ++++- 3 files changed, 23 insertions(+), 1 deletion(-) create mode 100644 20101004.html create mode 100644 20101005.html diff --git a/20101004.html b/20101004.html new file mode 100644 index 0000000..7b74a90 --- /dev/null +++ b/20101004.html @@ -0,0 +1,10 @@ +
+

20101004 - MSVC Optimizing Static Constant Function Tables?

+
+ + +Nope. Would be nice if the MSVC compiler could optimize FunctionJump() like FunctionIf() below,

#include <stdio.h>

typedef void (*Function)(const int);

static __forceinline void FunctionA(const int input) { printf("a=%d\n", input); }
static __forceinline void FunctionB(const int input) { printf("b=%d\n", input); }

static const Function function[2] = { FunctionA, FunctionB };
    
static __forceinline void FunctionJump(const int input) { function[input](input); }

static __forceinline void FunctionIf(const int input) {
    if(input == 0) FunctionA(input);
    if(input == 1) FunctionB(input); }

void main(void) {
    FunctionJump(0);
    FunctionJump(1);
    FunctionIf(0);
    FunctionIf(1); }


Trimmed section from assembly output /FAs,

PUBLIC _main
; Function compile flags: /Ogtpy
_TEXT SEGMENT
_main PROC

; 17   :     FunctionJump(0);

 push 0
 call DWORD PTR _function

; 18   :     FunctionJump(1);

 push 1
 call DWORD PTR _function+4

; 19   :     FunctionIf(0);

 push 0
 push OFFSET $SG3833
 call _printf

; 20   :     FunctionIf(1); }

 push 1
 push OFFSET $SG3837
 call _printf
 add esp, 24     ; 00000018H
 xor eax, eax
 ret 0
_main ENDP
+ +
+ + diff --git a/20101005.html b/20101005.html new file mode 100644 index 0000000..23ee6f8 --- /dev/null +++ b/20101005.html @@ -0,0 +1,9 @@ +
+

20101005 - MSVC Optimizing Static Constant Data Copy?

+
+ +Yes. All extra copies factored out.

#include <stdio.h>

typedef struct { 
    int a;
    int b;
    int c;
    int d;
} DataA;

typedef struct {
    int a;
    int d;
} DataB;

static const DataA dataA = { 0, 1, 2, 3 };

static __forceinline void DataCopy(
DataB* __restrict const dataB, const DataA* __restrict const dataA) {
    dataB->a = dataA->a;
    dataB->d = dataA->d; }

void main(void) {
    DataB dataB;
    DataCopy(&dataB, &dataA);
    printf("dataB.d = %d\n", dataB.d); }


Trimmed part of /FAs assembly output,

PUBLIC _main
EXTRN _printf:PROC
; Function compile flags: /Ogtpy
_TEXT SEGMENT
_main PROC

; 56   :     DataB dataB;
; 57   :     DataCopy(&dataB, &dataA);
; 58   :     printf("dataB.d = %d\n", dataB.d); }    

 push 3
 push OFFSET $SG3859
 call _printf
 add esp, 8
 xor eax, eax
 ret 0
_main ENDP
+ +
+ + diff --git a/index.html b/index.html index a96b541..6b713ee 100644 --- a/index.html +++ b/index.html @@ -40,7 +40,7 @@ and attempting to restore what I can from prior lost images.

@@ -248,6 +248,9 @@ and attempting to restore what I can from prior lost images. 20110907 - Parallel Programming With Clones

2010
+20101005 - MSVC Optimizing Static Constant Data Copy?
+20101004 - MSVC Optimizing Static Constant Function Tables?
+
20100108 - AntiPlanet2
20100105 - Game Engine Architecture
20100104 - OnLive Notes