From 473435b23a6e1320d2ee6536542d0503becf7bc2 Mon Sep 17 00:00:00 2001
From: Andrea Shepard <andrea@persephoneslair.org>
Date: Mon, 21 Nov 2016 08:30:17 +0000
Subject: [PATCH] Implement CHARSET_ACTION_BITMAP
---
src/backends/llvm/llvm_charset.c | 93 +++++++++++++++++++++++++++++---
1 file changed, 87 insertions(+), 6 deletions(-)
diff --git a/src/backends/llvm/llvm_charset.c b/src/backends/llvm/llvm_charset.c
index 16b0550d..cef110a5 100644
--- a/src/backends/llvm/llvm_charset.c
+++ b/src/backends/llvm/llvm_charset.c
@@ -797,6 +797,10 @@ static void h_llvm_pretty_print_charset_exec_plan(HAllocator *mm__, llvm_charset
}
/* Forward declares for IR-emission functions */
+static bool h_llvm_build_ir_for_bitmap(LLVMModuleRef mod, LLVMValueRef func, LLVMBuilderRef builder,
+ HCharset cs, uint8_t idx_start, uint8_t idx_end,
+ LLVMValueRef r,
+ LLVMBasicBlockRef in, LLVMBasicBlockRef yes, LLVMBasicBlockRef no);
static bool h_llvm_build_ir_for_scan(LLVMModuleRef mod, LLVMValueRef func, LLVMBuilderRef builder,
HCharset cs, uint8_t idx_start, uint8_t idx_end,
LLVMValueRef r,
@@ -810,6 +814,87 @@ static bool h_llvm_cep_to_ir(HAllocator* mm__,
LLVMValueRef r, llvm_charset_exec_plan_t *cep,
LLVMBasicBlockRef in, LLVMBasicBlockRef yes, LLVMBasicBlockRef no);
+/*
+ * Build IR for a CHARSET_ACTION_BITMAP
+ */
+
+static bool h_llvm_build_ir_for_bitmap(LLVMModuleRef mod, LLVMValueRef func, LLVMBuilderRef builder,
+ HCharset cs, uint8_t idx_start, uint8_t idx_end,
+ LLVMValueRef r,
+ LLVMBasicBlockRef in, LLVMBasicBlockRef yes, LLVMBasicBlockRef no) {
+ int i, j;
+ uint32_t bitmap_entry;
+
+ if (!cs) return false;
+ if (idx_start > idx_end) return false;
+
+ /*
+ * Embed a 8x32 bitmap in the IR, turn the input value into an index by
+ * right-shifting 5 bits, load the relevant bitmap byte, then derive a mask
+ * from the low-order 5 bits of the input value. & the mask with the bitmap
+ * byte, and compare. If non-zero, accept, otherwise reject.
+ */
+ LLVMPositionBuilderAtEnd(builder, in);
+
+ /* Construct the bitmap */
+ LLVMValueRef bitmap_entries[8];
+ for (i = 0; i < 8; ++i) {
+ bitmap_entry = 0x0;
+ /*
+ * Bit order; LSB is lowest-numbered char index 32*i, MSB is 32*i + 31.
+ * and then the mask we need is just 1 << (r & 0x1f).
+ */
+ for (j = 0; j < 32; ++j) {
+ /* Set the bit if necessary */
+ if (charset_isset(cs, (uint8_t)(32*i + j))) {
+ bitmap_entry |= ((uint32_t)(0x1) << j);
+ }
+ }
+
+ /* Make an LLVMValueRef for it */
+ bitmap_entries[i] = LLVMConstInt(LLVMInt32Type(), bitmap_entry, 0);
+ }
+ /* Now make an array out of them */
+ LLVMValueRef bitmap_initializer = LLVMConstArray(LLVMInt32Type(), bitmap_entries, 8);
+ /* ...and we need a global variable to stick it in to GEP it */
+ LLVMValueRef bitmap = LLVMAddGlobal(mod, LLVMTypeOf(bitmap_initializer), "bitmap");
+ LLVMSetInitializer(bitmap, bitmap_initializer);
+
+ /* Compute the index into the bitmap */
+ LLVMValueRef word_index = LLVMBuildLShr(builder, r,
+ LLVMConstInt(LLVMInt8Type(), 5, 0), "word_index");
+
+ /* Get a pointer to that word in the bitmap */
+ LLVMValueRef gep_indices[2];
+ gep_indices[0] = LLVMConstInt(LLVMInt32Type(), 0, 0);
+ gep_indices[1] = word_index;
+ LLVMValueRef bitmap_word_p =
+ LLVMBuildInBoundsGEP(builder, bitmap, gep_indices, 2, "bitmap_word_p");
+ LLVMValueRef bitmap_word =
+ LLVMBuildLoad(builder, bitmap_word_p, "bitmap_word");
+ /*
+ * Extract the low-order 5 bits of r, and expand to a 32-bit int for the
+ * mask
+ */
+ LLVMValueRef bit_index = LLVMBuildAnd(builder, r,
+ LLVMConstInt(LLVMInt8Type(), 0x1f, 0), "bit_index");
+ LLVMValueRef bit_index_zext = LLVMBuildZExt(builder, bit_index,
+ LLVMInt32Type(), "bit_index_zext");
+ /* Compute mask */
+ LLVMValueRef mask = LLVMBuildShl(builder, LLVMConstInt(LLVMInt32Type(), 1, 0),
+ bit_index_zext, "mask");
+ /* AND the mask with the bitmap word */
+ LLVMValueRef masked_bitmap_word = LLVMBuildAnd(builder, bitmap_word, mask,
+ "masked_bitmap_word");
+ /* Compare it to zero */
+ LLVMValueRef bitmap_icmp = LLVMBuildICmp(builder, LLVMIntNE,
+ masked_bitmap_word, LLVMConstInt(LLVMInt32Type(), 0, 0), "bitmap_icmp");
+ /* If not zero, the char is in the set */
+ LLVMBuildCondBr(builder, bitmap_icmp, yes, no);
+
+ return true;
+}
+
/*
* Build IR for a CHARSET_ACTION_SCAN
*/
@@ -916,12 +1001,8 @@ static bool h_llvm_cep_to_ir(HAllocator* mm__,
rv = true;
break;
case CHARSET_ACTION_BITMAP:
-#ifdef HAMMER_LLVM_CHARSET_DEBUG
- fprintf(stderr,
- "CHARSET_ACTION_BITMAP not yet implemented (cep %p)\n",
- (void *)cep);
-#endif /* defined(HAMMER_LLVM_CHARSET_DEBUG) */
- rv = false;
+ rv = h_llvm_build_ir_for_bitmap(mod, func, builder,
+ cep->cs, cep->idx_start, cep->idx_end, r, in, yes, no);
break;
case CHARSET_ACTION_COMPLEMENT:
/* This is trivial; just swap the 'yes' and 'no' outputs and build the child */
--
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