diff options
author | Brian Paul <brianp@vmware.com> | 2010-01-06 14:11:54 -0700 |
---|---|---|
committer | Brian Paul <brianp@vmware.com> | 2010-01-06 14:11:54 -0700 |
commit | db7f9b053b7982810a00bc4d944bb3dfa2b9aac9 (patch) | |
tree | 4881da2bcee31cc7a63507b4e923767f8685a4e1 /src | |
parent | 4e8d67af574af480fdcca79e23836464c86b2dee (diff) |
llvmpipe: more comments in flow builder code
Diffstat (limited to 'src')
-rw-r--r-- | src/gallium/drivers/llvmpipe/lp_bld_flow.c | 21 |
1 files changed, 20 insertions, 1 deletions
diff --git a/src/gallium/drivers/llvmpipe/lp_bld_flow.c b/src/gallium/drivers/llvmpipe/lp_bld_flow.c index 22b4310f06..e42b653b67 100644 --- a/src/gallium/drivers/llvmpipe/lp_bld_flow.c +++ b/src/gallium/drivers/llvmpipe/lp_bld_flow.c @@ -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], ¤t_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], ¤t_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); } |