Hello!
My last mail was misleading. The described behaviour (continue out of loop
etc.) occurs with mesa's current glsl compiler. The attached patch tries to
fix that.
I appologize for the faulty description and hope it was the cause for the lack
of feedback to my last mail.
I also attached two piglit tests to demonstrate the bug.
Fabian
On Friday 26 November 2010 02:09:31 Fabian Bieler wrote:
> Hello!
>
> This patch fixes a bug in the lower_jumps pass if lower_sub_return is set
> to true.
>
> Subroutines such as
>
> void sub() {
> for (int i = 0; i < 2; ++i) {
> if (i)
> return;
> }
> }
>
> a continue instruction is inserted outside of the loop.
>
> Subroutines such as
>
> void sub() {
> for (int j = 0; j < 2; ++j) {
> for (int i = 0; i < 2; ++i) {
> if (i)
> return;
> }
> }
> alter_some_global_variable();
> return;
> }
>
> get transformed to
>
> void sub() {
> bool return_flag = false;
> for (int j = 0; j < 2; ++j) {
> for (int i = 0; i < 2; ++i) {
> if (i) {
> return_flag = true;
> break;
> }
> }
> if (return_flag)
> break;
> }
> alter_some_global_variable();
> return;
> }
>
> Please review
>
> Fabian
From 001a40b4033f072c2683426d13bd67cbc793da8c Mon Sep 17 00:00:00 2001
From: Fabian Bieler <[email protected]>
Date: Wed, 1 Dec 2010 14:44:58 +0100
Subject: [PATCH] glsl: fix lowering conditional returns in subroutines
this fix applies to the lower_sub_return 'branch' of the lower_jumps pass
---
src/glsl/lower_jumps.cpp | 6 +++++-
1 files changed, 5 insertions(+), 1 deletions(-)
diff --git a/src/glsl/lower_jumps.cpp b/src/glsl/lower_jumps.cpp
index e1e7a5b..9009495 100644
--- a/src/glsl/lower_jumps.cpp
+++ b/src/glsl/lower_jumps.cpp
@@ -490,7 +490,11 @@ lower_continue:
if(this->loop.may_set_return_flag) {
assert(this->function.return_flag);
ir_if* return_if = new(ir) ir_if(new(ir) ir_dereference_variable(this->function.return_flag));
- return_if->then_instructions.push_tail(new(ir) ir_loop_jump(saved_loop.loop ? ir_loop_jump::jump_break : ir_loop_jump::jump_continue));
+ saved_loop.may_set_return_flag = true;
+ if(saved_loop.loop)
+ return_if->then_instructions.push_tail(new(ir) ir_loop_jump(ir_loop_jump::jump_break));
+ else
+ move_outer_block_inside(ir, &return_if->else_instructions);
ir->insert_after(return_if);
}
--
1.7.1
[require]
GL >= 2.0
GLSL >= 1.10
[vertex shader]
void main()
{
gl_Position = gl_Vertex;
}
[fragment shader]
float val = 0.0;
void sub() {
for (int i = 0; i < 3; ++i) {
if (i == 1)
return;
val = 0.5;
}
val = 1.0;
}
void main() {
sub();
gl_FragColor = vec4(val);
}
[test]
draw rect -1 -1 2 2
probe all rgb 0.5 0.5 0.5 0.5
[require]
GL >= 2.0
GLSL >= 1.10
[vertex shader]
void main()
{
gl_Position = gl_Vertex;
}
[fragment shader]
float val = 0.0;
void sub() {
for (int i = 0; i < 3; ++i) {
for (int j = 0; j < 3; ++j) {
if (i == 1 && j == 1)
return;
val = 0.5;
}
}
val = 1.0;
}
void main() {
sub();
gl_FragColor = vec4(val);
}
[test]
draw rect -1 -1 2 2
probe all rgb 0.5 0.5 0.5 0.5
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