From 693667bf88abcb60332a6f94c8f06a9fe7d62613 Mon Sep 17 00:00:00 2001
From: José Fonseca <jfonseca@vmware.com>
Date: Sun, 10 Oct 2010 19:05:05 +0100
Subject: gallivm: Use variables instead of Phis in loops.

With this commit all explicit Phi emission is now gone.
---
 src/gallium/auxiliary/gallivm/lp_bld_flow.c | 62 ++++++++++-------------------
 src/gallium/auxiliary/gallivm/lp_bld_flow.h |  3 +-
 2 files changed, 23 insertions(+), 42 deletions(-)

diff --git a/src/gallium/auxiliary/gallivm/lp_bld_flow.c b/src/gallium/auxiliary/gallivm/lp_bld_flow.c
index 9d1a74f5d1..f9d061fcb4 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_flow.c
+++ b/src/gallium/auxiliary/gallivm/lp_bld_flow.c
@@ -201,59 +201,27 @@ lp_build_loop_begin(LLVMBuilderRef builder,
                     LLVMValueRef start,
                     struct lp_build_loop_state *state)
 {
-   LLVMBasicBlockRef block = LLVMGetInsertBlock(builder);
-   LLVMValueRef function = LLVMGetBasicBlockParent(block);
+   state->block = lp_build_insert_new_block(builder, "loop_begin");
+
+   state->counter_var = lp_build_alloca(builder, LLVMTypeOf(start), "loop_counter");
 
-   state->block = LLVMAppendBasicBlock(function, "loop");
+   LLVMBuildStore(builder, start, state->counter_var);
 
    LLVMBuildBr(builder, state->block);
 
    LLVMPositionBuilderAtEnd(builder, state->block);
 
-   state->counter = LLVMBuildPhi(builder, LLVMTypeOf(start), "");
-
-   LLVMAddIncoming(state->counter, &start, &block, 1);
-
+   state->counter = LLVMBuildLoad(builder, state->counter_var, "");
 }
 
 
-void
-lp_build_loop_end(LLVMBuilderRef builder,
-                  LLVMValueRef end,
-                  LLVMValueRef step,
-                  struct lp_build_loop_state *state)
-{
-   LLVMBasicBlockRef block = LLVMGetInsertBlock(builder);
-   LLVMValueRef function = LLVMGetBasicBlockParent(block);
-   LLVMValueRef next;
-   LLVMValueRef cond;
-   LLVMBasicBlockRef after_block;
-
-   if (!step)
-      step = LLVMConstInt(LLVMTypeOf(end), 1, 0);
-
-   next = LLVMBuildAdd(builder, state->counter, step, "");
-
-   cond = LLVMBuildICmp(builder, LLVMIntNE, next, end, "");
-
-   after_block = LLVMAppendBasicBlock(function, "");
-
-   LLVMBuildCondBr(builder, cond, after_block, state->block);
-
-   LLVMAddIncoming(state->counter, &next, &block, 1);
-
-   LLVMPositionBuilderAtEnd(builder, after_block);
-}
-
 void
 lp_build_loop_end_cond(LLVMBuilderRef builder,
                        LLVMValueRef end,
                        LLVMValueRef step,
-                       int llvm_cond,
+                       LLVMIntPredicate llvm_cond,
                        struct lp_build_loop_state *state)
 {
-   LLVMBasicBlockRef block = LLVMGetInsertBlock(builder);
-   LLVMValueRef function = LLVMGetBasicBlockParent(block);
    LLVMValueRef next;
    LLVMValueRef cond;
    LLVMBasicBlockRef after_block;
@@ -263,15 +231,27 @@ lp_build_loop_end_cond(LLVMBuilderRef builder,
 
    next = LLVMBuildAdd(builder, state->counter, step, "");
 
+   LLVMBuildStore(builder, next, state->counter_var);
+
    cond = LLVMBuildICmp(builder, llvm_cond, next, end, "");
 
-   after_block = LLVMAppendBasicBlock(function, "");
+   after_block = lp_build_insert_new_block(builder, "loop_end");
 
    LLVMBuildCondBr(builder, cond, after_block, state->block);
 
-   LLVMAddIncoming(state->counter, &next, &block, 1);
-
    LLVMPositionBuilderAtEnd(builder, after_block);
+
+   state->counter = LLVMBuildLoad(builder, state->counter_var, "");
+}
+
+
+void
+lp_build_loop_end(LLVMBuilderRef builder,
+                  LLVMValueRef end,
+                  LLVMValueRef step,
+                  struct lp_build_loop_state *state)
+{
+   lp_build_loop_end_cond(builder, end, step, LLVMIntNE, state);
 }
 
 
diff --git a/src/gallium/auxiliary/gallivm/lp_bld_flow.h b/src/gallium/auxiliary/gallivm/lp_bld_flow.h
index e21d9de280..e729ee6eaa 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_flow.h
+++ b/src/gallium/auxiliary/gallivm/lp_bld_flow.h
@@ -108,6 +108,7 @@ lp_build_mask_end(struct lp_build_mask_context *mask);
 struct lp_build_loop_state
 {
   LLVMBasicBlockRef block;
+  LLVMValueRef counter_var;
   LLVMValueRef counter;
 };
 
@@ -128,7 +129,7 @@ void
 lp_build_loop_end_cond(LLVMBuilderRef builder,
                        LLVMValueRef end,
                        LLVMValueRef step,
-                       int cond, /* LLVM condition */
+                       LLVMIntPredicate cond,
                        struct lp_build_loop_state *state);
 
 
-- 
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