* Enumeration of all possible flow constructs.
*/
enum lp_build_flow_construct_kind {
- LP_BUILD_FLOW_SCOPE,
LP_BUILD_FLOW_SKIP,
LP_BUILD_FLOW_IF
};
-/**
- * Variable declaration scope.
- */
-struct lp_build_flow_scope
-{
- /** Number of variables declared in this scope */
- unsigned num_variables;
-};
-
-
/**
* Early exit. Useful to skip to the end of a function or block when
* the execution mask becomes zero or when there is an error condition.
{
/** Block to skip to */
LLVMBasicBlockRef block;
-
- /** Number of variables declared at the beginning */
- unsigned num_variables;
-
- LLVMValueRef *phi; /**< array [num_variables] */
};
*/
struct lp_build_flow_if
{
- unsigned num_variables;
-
- LLVMValueRef *phi; /**< array [num_variables] */
-
LLVMValueRef condition;
LLVMBasicBlockRef entry_block, true_block, false_block, merge_block;
};
*/
union lp_build_flow_construct_data
{
- struct lp_build_flow_scope scope;
struct lp_build_flow_skip skip;
struct lp_build_flow_if ifthen;
};
*/
struct lp_build_flow_construct constructs[LP_BUILD_FLOW_MAX_DEPTH];
unsigned num_constructs;
-
- /**
- * Variable stack
- */
- LLVMValueRef *variables[LP_BUILD_FLOW_MAX_VARIABLES];
- unsigned num_variables;
};
lp_build_flow_destroy(struct lp_build_flow_context *flow)
{
assert(flow->num_constructs == 0);
- assert(flow->num_variables == 0);
FREE(flow);
}
}
-/**
- * Begin a variable scope.
- *
- *
- */
-void
-lp_build_flow_scope_begin(struct lp_build_flow_context *flow)
-{
- struct lp_build_flow_scope *scope;
-
- scope = &lp_build_flow_push(flow, LP_BUILD_FLOW_SCOPE)->scope;
- if(!scope)
- return;
-
- scope->num_variables = 0;
-}
-
-
-/**
- * Declare a variable.
- *
- * A variable is a named entity which can have different LLVMValueRef's at
- * different points of the program. This is relevant for control flow because
- * when there are multiple branches to a same location we need to replace
- * the variable's value with a Phi function as explained in
- * http://en.wikipedia.org/wiki/Static_single_assignment_form .
- *
- * We keep track of variables by keeping around a pointer to where they're
- * current.
- *
- * There are a few cautions to observe:
- *
- * - Variable's value must not be NULL. If there is no initial value then
- * LLVMGetUndef() should be used.
- *
- * - Variable's value must be kept up-to-date. If the variable is going to be
- * modified by a function then a pointer should be passed so that its value
- * is accurate. Failure to do this will cause some of the variables'
- * transient values to be lost, leading to wrong results.
- *
- * - A program should be written from top to bottom, by always appending
- * instructions to the bottom with a single LLVMBuilderRef. Inserting and/or
- * modifying existing statements will most likely lead to wrong results.
- *
- */
-void
-lp_build_flow_scope_declare(struct lp_build_flow_context *flow,
- LLVMValueRef *variable)
-{
- struct lp_build_flow_scope *scope;
-
- scope = &lp_build_flow_peek(flow, LP_BUILD_FLOW_SCOPE)->scope;
- if(!scope)
- return;
-
- assert(*variable);
- if(!*variable)
- return;
-
- assert(flow->num_variables < LP_BUILD_FLOW_MAX_VARIABLES);
- if(flow->num_variables >= LP_BUILD_FLOW_MAX_VARIABLES)
- return;
-
- flow->variables[flow->num_variables++] = variable;
- ++scope->num_variables;
-}
-
-
-void
-lp_build_flow_scope_end(struct lp_build_flow_context *flow)
-{
- struct lp_build_flow_scope *scope;
-
- scope = &lp_build_flow_pop(flow, LP_BUILD_FLOW_SCOPE)->scope;
- if(!scope)
- return;
-
- assert(flow->num_variables >= scope->num_variables);
- if(flow->num_variables < scope->num_variables) {
- flow->num_variables = 0;
- return;
- }
-
- flow->num_variables -= scope->num_variables;
-}
-
-
/**
* Note: this function has no dependencies on the flow code and could
* be used elsewhere.
{
struct lp_build_flow_skip *skip;
LLVMBuilderRef builder;
- unsigned i;
skip = &lp_build_flow_push(flow, LP_BUILD_FLOW_SKIP)->skip;
if(!skip)
/* 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;
- return;
- }
-
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]), "");
-
LLVMDisposeBuilder(builder);
}
LLVMValueRef cond)
{
struct lp_build_flow_skip *skip;
- LLVMBasicBlockRef current_block;
LLVMBasicBlockRef new_block;
- unsigned i;
skip = &lp_build_flow_peek(flow, LP_BUILD_FLOW_SKIP)->skip;
if(!skip)
return;
- current_block = LLVMGetInsertBlock(flow->builder);
-
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]);
- assert(LLVMTypeOf(skip->phi[i]) == LLVMTypeOf(*flow->variables[i]));
- LLVMAddIncoming(skip->phi[i], flow->variables[i], ¤t_block, 1);
- }
-
/* if cond is true, goto skip->block, else goto new_block */
LLVMBuildCondBr(flow->builder, cond, skip->block, new_block);
lp_build_flow_skip_end(struct lp_build_flow_context *flow)
{
struct lp_build_flow_skip *skip;
- LLVMBasicBlockRef current_block;
- unsigned i;
skip = &lp_build_flow_pop(flow, LP_BUILD_FLOW_SKIP)->skip;
if(!skip)
return;
- 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]);
- assert(LLVMTypeOf(skip->phi[i]) == LLVMTypeOf(*flow->variables[i]));
- LLVMAddIncoming(skip->phi[i], flow->variables[i], ¤t_block, 1);
- *flow->variables[i] = skip->phi[i];
- }
-
/* goto block */
LLVMBuildBr(flow->builder, skip->block);
LLVMPositionBuilderAtEnd(flow->builder, skip->block);
-
- FREE(skip->phi);
}
{
LLVMBasicBlockRef block = LLVMGetInsertBlock(builder);
struct lp_build_flow_if *ifthen;
- unsigned i;
memset(ctx, 0, sizeof(*ctx));
ctx->builder = builder;
ifthen = &lp_build_flow_push(flow, LP_BUILD_FLOW_IF)->ifthen;
assert(ifthen);
- ifthen->num_variables = flow->num_variables;
ifthen->condition = condition;
ifthen->entry_block = block;
- /* create a Phi node for each variable in this flow scope */
- ifthen->phi = MALLOC(ifthen->num_variables * sizeof(*ifthen->phi));
- if (!ifthen->phi) {
- ifthen->num_variables = 0;
- return;
- }
-
/* create endif/merge basic block for the phi functions */
ifthen->merge_block = lp_build_insert_new_block(builder, "endif-block");
LLVMPositionBuilderAtEnd(builder, ifthen->merge_block);
- /* create a phi node for each variable */
- for (i = 0; i < flow->num_variables; i++) {
- ifthen->phi[i] = LLVMBuildPhi(builder, LLVMTypeOf(*flow->variables[i]), "");
-
- /* add add the initial value of the var from the entry block */
- if (!LLVMIsUndef(*flow->variables[i]))
- LLVMAddIncoming(ifthen->phi[i], flow->variables[i],
- &ifthen->entry_block, 1);
- }
-
/* create/insert true_block before merge_block */
ifthen->true_block = LLVMInsertBasicBlock(ifthen->merge_block, "if-true-block");
{
struct lp_build_flow_context *flow = ctx->flow;
struct lp_build_flow_if *ifthen;
- unsigned i;
ifthen = &lp_build_flow_peek(flow, LP_BUILD_FLOW_IF)->ifthen;
assert(ifthen);
- /* for each variable, update the Phi node with a (variable, block) pair */
- LLVMPositionBuilderAtEnd(ctx->builder, ifthen->merge_block);
- for (i = 0; i < flow->num_variables; i++) {
- assert(*flow->variables[i]);
- LLVMAddIncoming(ifthen->phi[i], flow->variables[i], &ifthen->true_block, 1);
- }
-
/* create/insert false_block before the merge block */
ifthen->false_block = LLVMInsertBasicBlock(ifthen->merge_block, "if-false-block");
{
struct lp_build_flow_context *flow = ctx->flow;
struct lp_build_flow_if *ifthen;
- LLVMBasicBlockRef curBlock = LLVMGetInsertBlock(ctx->builder);
- unsigned i;
ifthen = &lp_build_flow_pop(flow, LP_BUILD_FLOW_IF)->ifthen;
assert(ifthen);
/* Insert branch to the merge block from current block */
LLVMBuildBr(ctx->builder, ifthen->merge_block);
- if (ifthen->false_block) {
- LLVMPositionBuilderAtEnd(ctx->builder, ifthen->merge_block);
- /* for each variable, update the Phi node with a (variable, block) pair */
- for (i = 0; i < flow->num_variables; i++) {
- assert(*flow->variables[i]);
- LLVMAddIncoming(ifthen->phi[i], flow->variables[i], &curBlock, 1);
- /* replace the variable ref with the phi function */
- *flow->variables[i] = ifthen->phi[i];
- }
- }
- else {
- /* no else clause */
- LLVMPositionBuilderAtEnd(ctx->builder, ifthen->merge_block);
- for (i = 0; i < flow->num_variables; i++) {
- assert(*flow->variables[i]);
- LLVMAddIncoming(ifthen->phi[i], flow->variables[i], &ifthen->true_block, 1);
-
- /* replace the variable ref with the phi function */
- *flow->variables[i] = ifthen->phi[i];
- }
- }
-
- FREE(ifthen->phi);
-
/***
*** Now patch in the various branch instructions.
***/
projects / mesa.git / commitdiff