From bc0f82cad854acb839f2202fbe87bb30951be710 Mon Sep 17 00:00:00 2001
From: Sebastien Bourdeauducq <sb@m-labs.hk>
Date: Tue, 2 Nov 2021 14:00:28 +0800
Subject: [PATCH] Revert "nac3artiq/codegen: fixed smax problem"

We have LLVM 12 now and can use the intrinsic.

This reverts commit 98d9f73afbfb3a3a296eb24e9c29fe3646c7da14.
---
 nac3artiq/src/codegen.rs | 47 +++++++++++++++++++++++++---------------
 1 file changed, 29 insertions(+), 18 deletions(-)

diff --git a/nac3artiq/src/codegen.rs b/nac3artiq/src/codegen.rs
index 002ad369..cb79c549 100644
--- a/nac3artiq/src/codegen.rs
+++ b/nac3artiq/src/codegen.rs
@@ -6,7 +6,7 @@ use nac3core::{
 
 use rustpython_parser::ast::{Expr, ExprKind, Located, Stmt, StmtKind, StrRef};
 
-use inkwell::values::{BasicValueEnum, IntValue};
+use inkwell::values::BasicValueEnum;
 
 use crate::timeline::TimeFns;
 
@@ -30,17 +30,6 @@ impl<'a> ArtiqCodeGenerator<'a> {
     }
 }
 
-fn max_val<'ctx, 'a>(
-    ctx: &mut CodeGenContext<'ctx, 'a>,
-    a: IntValue<'ctx>,
-    b: IntValue<'ctx>,
-) -> IntValue<'ctx> {
-    let cmp = ctx
-        .builder
-        .build_int_compare(inkwell::IntPredicate::SGT, a, b, "gt");
-    ctx.builder.build_select(cmp, a, b, "max").into_int_value()
-}
-
 impl<'b> CodeGenerator for ArtiqCodeGenerator<'b> {
     fn get_name(&self) -> &str {
         &self.name
@@ -57,7 +46,20 @@ impl<'b> CodeGenerator for ArtiqCodeGenerator<'b> {
         if let Some(end) = self.end.clone() {
             let old_end = self.gen_expr(ctx, &end).unwrap();
             let now = self.timeline.emit_now_mu(ctx);
-            let max = max_val(ctx, old_end.into_int_value(), now.into_int_value());
+            let smax = ctx.module.get_function("llvm.smax.i64").unwrap_or_else(|| {
+                let i64 = ctx.ctx.i64_type();
+                ctx.module.add_function(
+                    "llvm.smax.i64",
+                    i64.fn_type(&[i64.into(), i64.into()], false),
+                    None,
+                )
+            });
+            let max = ctx
+                .builder
+                .build_call(smax, &[old_end, now], "smax")
+                .try_as_basic_value()
+                .left()
+                .unwrap();
             let end_store = self.gen_store_target(ctx, &end);
             ctx.builder.build_store(end_store, max);
         }
@@ -152,11 +154,20 @@ impl<'b> CodeGenerator for ArtiqCodeGenerator<'b> {
                         // inside a parallel block, should update the outer max now_mu
                         if let Some(old_end) = &old_end {
                             let outer_end_val = self.gen_expr(ctx, old_end).unwrap();
-                            let max = max_val(
-                                ctx,
-                                end_val.into_int_value(),
-                                outer_end_val.into_int_value(),
-                            );
+                            let smax = ctx.module.get_function("llvm.smax.i64").unwrap_or_else(|| {
+                                let i64 = ctx.ctx.i64_type();
+                                ctx.module.add_function(
+                                    "llvm.smax.i64",
+                                    i64.fn_type(&[i64.into(), i64.into()], false),
+                                    None,
+                                )
+                            });
+                            let max = ctx
+                                .builder
+                                .build_call(smax, &[end_val, outer_end_val], "smax")
+                                .try_as_basic_value()
+                                .left()
+                                .unwrap();
                             let outer_end = self.gen_store_target(ctx, old_end);
                             ctx.builder.build_store(outer_end, max);
                         }