+/**
+ * Helper function that builds an LLVM IR PHI node and immediately adds
+ * incoming edges.
+ */
+LLVMValueRef
+ac_build_phi(struct ac_llvm_context *ctx, LLVMTypeRef type,
+ unsigned count_incoming, LLVMValueRef *values,
+ LLVMBasicBlockRef *blocks)
+{
+ LLVMValueRef phi = LLVMBuildPhi(ctx->builder, type, "");
+ LLVMAddIncoming(phi, values, blocks, count_incoming);
+ return phi;
+}
+
+/* Prevent optimizations (at least of memory accesses) across the current
+ * point in the program by emitting empty inline assembly that is marked as
+ * having side effects.
+ *
+ * Optionally, a value can be passed through the inline assembly to prevent
+ * LLVM from hoisting calls to ReadNone functions.
+ */
+void
+ac_build_optimization_barrier(struct ac_llvm_context *ctx,
+ LLVMValueRef *pvgpr)
+{
+ static int counter = 0;
+
+ LLVMBuilderRef builder = ctx->builder;
+ char code[16];
+
+ snprintf(code, sizeof(code), "; %d", p_atomic_inc_return(&counter));
+
+ if (!pvgpr) {
+ LLVMTypeRef ftype = LLVMFunctionType(ctx->voidt, NULL, 0, false);
+ LLVMValueRef inlineasm = LLVMConstInlineAsm(ftype, code, "", true, false);
+ LLVMBuildCall(builder, inlineasm, NULL, 0, "");
+ } else {
+ LLVMTypeRef ftype = LLVMFunctionType(ctx->i32, &ctx->i32, 1, false);
+ LLVMValueRef inlineasm = LLVMConstInlineAsm(ftype, code, "=v,0", true, false);
+ LLVMValueRef vgpr = *pvgpr;
+ LLVMTypeRef vgpr_type = LLVMTypeOf(vgpr);
+ unsigned vgpr_size = ac_get_type_size(vgpr_type);
+ LLVMValueRef vgpr0;
+
+ assert(vgpr_size % 4 == 0);
+
+ vgpr = LLVMBuildBitCast(builder, vgpr, LLVMVectorType(ctx->i32, vgpr_size / 4), "");
+ vgpr0 = LLVMBuildExtractElement(builder, vgpr, ctx->i32_0, "");
+ vgpr0 = LLVMBuildCall(builder, inlineasm, &vgpr0, 1, "");
+ vgpr = LLVMBuildInsertElement(builder, vgpr, vgpr0, ctx->i32_0, "");
+ vgpr = LLVMBuildBitCast(builder, vgpr, vgpr_type, "");
+
+ *pvgpr = vgpr;
+ }
+}
+
+LLVMValueRef
+ac_build_ballot(struct ac_llvm_context *ctx,
+ LLVMValueRef value)
+{
+ LLVMValueRef args[3] = {
+ value,
+ ctx->i32_0,
+ LLVMConstInt(ctx->i32, LLVMIntNE, 0)
+ };
+
+ /* We currently have no other way to prevent LLVM from lifting the icmp
+ * calls to a dominating basic block.
+ */
+ ac_build_optimization_barrier(ctx, &args[0]);
+
+ if (LLVMTypeOf(args[0]) != ctx->i32)
+ args[0] = LLVMBuildBitCast(ctx->builder, args[0], ctx->i32, "");
+
+ return ac_build_intrinsic(ctx,
+ "llvm.amdgcn.icmp.i32",
+ ctx->i64, args, 3,
+ AC_FUNC_ATTR_NOUNWIND |
+ AC_FUNC_ATTR_READNONE |
+ AC_FUNC_ATTR_CONVERGENT);
+}
+
+LLVMValueRef
+ac_build_vote_all(struct ac_llvm_context *ctx, LLVMValueRef value)
+{
+ LLVMValueRef active_set = ac_build_ballot(ctx, ctx->i32_1);
+ LLVMValueRef vote_set = ac_build_ballot(ctx, value);
+ return LLVMBuildICmp(ctx->builder, LLVMIntEQ, vote_set, active_set, "");
+}
+
+LLVMValueRef
+ac_build_vote_any(struct ac_llvm_context *ctx, LLVMValueRef value)
+{
+ LLVMValueRef vote_set = ac_build_ballot(ctx, value);
+ return LLVMBuildICmp(ctx->builder, LLVMIntNE, vote_set,
+ LLVMConstInt(ctx->i64, 0, 0), "");
+}
+
+LLVMValueRef
+ac_build_vote_eq(struct ac_llvm_context *ctx, LLVMValueRef value)
+{
+ LLVMValueRef active_set = ac_build_ballot(ctx, ctx->i32_1);
+ LLVMValueRef vote_set = ac_build_ballot(ctx, value);
+
+ LLVMValueRef all = LLVMBuildICmp(ctx->builder, LLVMIntEQ,
+ vote_set, active_set, "");
+ LLVMValueRef none = LLVMBuildICmp(ctx->builder, LLVMIntEQ,
+ vote_set,
+ LLVMConstInt(ctx->i64, 0, 0), "");
+ return LLVMBuildOr(ctx->builder, all, none, "");
+}
+