From e6ecd22140fe6c6e8ac26966c8409f7254370479 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Marek=20Ol=C5=A1=C3=A1k?= <marek.olsak@amd.com>
Date: Tue, 23 Aug 2022 00:13:37 -0400
Subject: [PATCH] mesa: make glPopMatrix a no-op if the matrix hasn't changed

This happens a lot with viewperf because glMultMatrixf contains identity
matrices.

Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/18828>
---
 src/mesa/main/matrix.c | 15 ++++++++++++++-
 src/mesa/main/mtypes.h |  1 +
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/src/mesa/main/matrix.c b/src/mesa/main/matrix.c
index ac23e70..0793cb1 100644
--- a/src/mesa/main/matrix.c
+++ b/src/mesa/main/matrix.c
@@ -122,6 +122,7 @@ static void matrix_frustum(struct gl_matrix_stack* stack,
                         (GLfloat) left, (GLfloat) right,
                         (GLfloat) bottom, (GLfloat) top,
                         (GLfloat) nearval, (GLfloat) farval);
+   stack->ChangedSincePush = true;
    ctx->NewState |= stack->DirtyFlag;
 }
 
@@ -203,6 +204,7 @@ matrix_ortho(struct gl_matrix_stack* stack,
                        (GLfloat) left, (GLfloat) right,
              (GLfloat) bottom, (GLfloat) top,
              (GLfloat) nearval, (GLfloat) farval );
+   stack->ChangedSincePush = true;
    ctx->NewState |= stack->DirtyFlag;
 }
 
@@ -328,6 +330,7 @@ push_matrix(struct gl_context *ctx, struct gl_matrix_stack *stack,
                           &stack->Stack[stack->Depth]);
    stack->Depth++;
    stack->Top = &(stack->Stack[stack->Depth]);
+   stack->ChangedSincePush = false;
 }
 
 
@@ -377,7 +380,8 @@ pop_matrix( struct gl_context *ctx, struct gl_matrix_stack *stack )
    /* If the popped matrix is the same as the current one, treat it as
     * a no-op change.
     */
-   if (memcmp(stack->Top, &stack->Stack[stack->Depth],
+   if (stack->ChangedSincePush &&
+       memcmp(stack->Top, &stack->Stack[stack->Depth],
               sizeof(GLmatrix))) {
       FLUSH_VERTICES(ctx, 0, 0);
       ctx->NewState |= stack->DirtyFlag;
@@ -450,6 +454,7 @@ _mesa_load_identity_matrix(struct gl_context *ctx, struct gl_matrix_stack *stack
    FLUSH_VERTICES(ctx, 0, 0);
 
    _math_matrix_set_identity(stack->Top);
+   stack->ChangedSincePush = true;
    ctx->NewState |= stack->DirtyFlag;
 }
 
@@ -495,6 +500,7 @@ _mesa_load_matrix(struct gl_context *ctx, struct gl_matrix_stack *stack,
    if (memcmp(m, stack->Top->m, 16 * sizeof(GLfloat)) != 0) {
       FLUSH_VERTICES(ctx, 0, 0);
       _math_matrix_loadf(stack->Top, m);
+      stack->ChangedSincePush = true;
       ctx->NewState |= stack->DirtyFlag;
    }
 }
@@ -583,6 +589,7 @@ matrix_mult(struct gl_matrix_stack *stack, const GLfloat *m, const char* caller)
 
    FLUSH_VERTICES(ctx, 0, 0);
    _math_matrix_mul_floats(stack->Top, m);
+   stack->ChangedSincePush = true;
    ctx->NewState |= stack->DirtyFlag;
 }
 
@@ -628,6 +635,7 @@ matrix_rotate(struct gl_matrix_stack *stack, GLfloat angle,
    FLUSH_VERTICES(ctx, 0, 0);
    if (angle != 0.0F) {
       _math_matrix_rotate(stack->Top, angle, x, y, z);
+      stack->ChangedSincePush = true;
       ctx->NewState |=stack->DirtyFlag;
    }
 }
@@ -688,6 +696,7 @@ _mesa_Scalef( GLfloat x, GLfloat y, GLfloat z )
 
    FLUSH_VERTICES(ctx, 0, 0);
    _math_matrix_scale( ctx->CurrentStack->Top, x, y, z);
+   ctx->CurrentStack->ChangedSincePush = true;
    ctx->NewState |= ctx->CurrentStack->DirtyFlag;
 }
 
@@ -704,6 +713,7 @@ _mesa_MatrixScalefEXT( GLenum matrixMode, GLfloat x, GLfloat y, GLfloat z )
 
    FLUSH_VERTICES(ctx, 0, 0);
    _math_matrix_scale(stack->Top, x, y, z);
+   stack->ChangedSincePush = true;
    ctx->NewState |= stack->DirtyFlag;
 }
 
@@ -728,6 +738,7 @@ _mesa_Translatef( GLfloat x, GLfloat y, GLfloat z )
 
    FLUSH_VERTICES(ctx, 0, 0);
    _math_matrix_translate( ctx->CurrentStack->Top, x, y, z);
+   ctx->CurrentStack->ChangedSincePush = true;
    ctx->NewState |= ctx->CurrentStack->DirtyFlag;
 }
 
@@ -743,6 +754,7 @@ _mesa_MatrixTranslatefEXT( GLenum matrixMode, GLfloat x, GLfloat y, GLfloat z )
 
    FLUSH_VERTICES(ctx, 0, 0);
    _math_matrix_translate(stack->Top, x, y, z);
+   stack->ChangedSincePush = true;
    ctx->NewState |= stack->DirtyFlag;
 }
 
@@ -1004,6 +1016,7 @@ init_matrix_stack(struct gl_matrix_stack *stack,
    stack->StackSize = 1;
    _math_matrix_ctr(&stack->Stack[0]);
    stack->Top = stack->Stack;
+   stack->ChangedSincePush = false;
 }
 
 /**
diff --git a/src/mesa/main/mtypes.h b/src/mesa/main/mtypes.h
index 7b3d30e..42bea71 100644
--- a/src/mesa/main/mtypes.h
+++ b/src/mesa/main/mtypes.h
@@ -2791,6 +2791,7 @@ struct gl_matrix_stack
    GLuint Depth;       /**< 0 <= Depth < MaxDepth */
    GLuint MaxDepth;    /**< size of Stack[] array */
    GLuint DirtyFlag;   /**< _NEW_MODELVIEW or _NEW_PROJECTION, for example */
+   bool ChangedSincePush;
 };
 
 
-- 
2.7.4