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llvmpipe: more comments in flow builder code

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This commit is contained in:
Brian Paul 2010-01-06 14:11:54 -07:00
parent 4e8d67af57
commit db7f9b053b
1 changed files with 20 additions and 1 deletions
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21
src/gallium/drivers/llvmpipe/lp_bld_flow.c
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@ -310,6 +310,11 @@ lp_build_flow_insert_block(struct lp_build_flow_context *flow)
return new_block;
}
/**
* Begin a "skip" block. Inside this block we can test a condition and
* skip to the end of the block if the condition is false.
*/
void
lp_build_flow_skip_begin(struct lp_build_flow_context *flow)
{
@ -321,13 +326,16 @@ lp_build_flow_skip_begin(struct lp_build_flow_context *flow)
if(!skip)
return;
/* create new basic block */
skip->block = lp_build_flow_insert_block(flow);
skip->num_variables = flow->num_variables;
if(!skip->num_variables) {
skip->phi = NULL;
return;
}
/* Allocate a Phi node for each variable in this skip scope */
skip->phi = MALLOC(skip->num_variables * sizeof *skip->phi);
if(!skip->phi) {
skip->num_variables = 0;
@ -337,6 +345,7 @@ lp_build_flow_skip_begin(struct lp_build_flow_context *flow)
builder = LLVMCreateBuilder();
LLVMPositionBuilderAtEnd(builder, skip->block);
/* create a Phi node for each variable */
for(i = 0; i < skip->num_variables; ++i)
skip->phi[i] = LLVMBuildPhi(builder, LLVMTypeOf(*flow->variables[i]), "");
@ -344,6 +353,10 @@ lp_build_flow_skip_begin(struct lp_build_flow_context *flow)
}
/**
* Insert code to test a condition and branch to the end of the current
* skip block if the condition is true.
*/
void
lp_build_flow_skip_cond_break(struct lp_build_flow_context *flow,
LLVMValueRef cond)
@ -361,15 +374,17 @@ lp_build_flow_skip_cond_break(struct lp_build_flow_context *flow,
new_block = lp_build_flow_insert_block(flow);
/* for each variable, update the Phi node with a (variable, block) pair */
for(i = 0; i < skip->num_variables; ++i) {
assert(*flow->variables[i]);
LLVMAddIncoming(skip->phi[i], flow->variables[i], &current_block, 1);
}
/* if cond is true, goto skip->block, else goto new_block */
LLVMBuildCondBr(flow->builder, cond, skip->block, new_block);
LLVMPositionBuilderAtEnd(flow->builder, new_block);
}
}
void
@ -385,12 +400,14 @@ lp_build_flow_skip_end(struct lp_build_flow_context *flow)
current_block = LLVMGetInsertBlock(flow->builder);
/* add (variable, block) tuples to the phi nodes */
for(i = 0; i < skip->num_variables; ++i) {
assert(*flow->variables[i]);
LLVMAddIncoming(skip->phi[i], flow->variables[i], &current_block, 1);
*flow->variables[i] = skip->phi[i];
}
/* goto block */
LLVMBuildBr(flow->builder, skip->block);
LLVMPositionBuilderAtEnd(flow->builder, skip->block);
@ -407,12 +424,14 @@ lp_build_mask_check(struct lp_build_mask_context *mask)
LLVMBuilderRef builder = mask->flow->builder;
LLVMValueRef cond;
/* cond = (mask == 0) */
cond = LLVMBuildICmp(builder,
LLVMIntEQ,
LLVMBuildBitCast(builder, mask->value, mask->reg_type, ""),
LLVMConstNull(mask->reg_type),
"");
/* if cond, goto end of block */
lp_build_flow_skip_cond_break(mask->flow, cond);
}