From 3ea594f42b0ba8abf361a43d4042dd293b3b71c2 Mon Sep 17 00:00:00 2001
From: Georg Lehmann <dadschoorse@gmail.com>
Date: Mon, 18 May 2026 14:47:29 +0200
Subject: [PATCH] ac/llvm: never create ffmaz for broken llvm

The workaround wasn't proper fused ffma.

Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/41649>
---
 src/amd/common/nir/ac_nir.c   | 12 ++++++++++++
 src/amd/llvm/ac_nir_to_llvm.c | 14 ++------------
 2 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/src/amd/common/nir/ac_nir.c b/src/amd/common/nir/ac_nir.c
index 610fa31aaff..66c9be306b1 100644
--- a/src/amd/common/nir/ac_nir.c
+++ b/src/amd/common/nir/ac_nir.c
@@ -10,6 +10,10 @@
 #include "nir_builder.h"
 #include "nir_intrinsics.h"
 
+#if AMD_LLVM_AVAILABLE
+#include <llvm/Config/llvm-config.h>
+#endif
+
 /* Set NIR options shared by ACO, LLVM, RADV, and radeonsi. */
 void ac_nir_set_options(const struct ac_compiler_info *info, bool use_llvm,
                         nir_shader_compiler_options *options)
@@ -144,6 +148,14 @@ void ac_nir_set_options(const struct ac_compiler_info *info, bool use_llvm,
    options->max_workgroup_count[1] = UINT16_MAX;
    options->max_workgroup_count[2] = UINT16_MAX;
    options->max_samples = 8;
+
+   /* Workaround for LLVM bug that crashes when using legacy fma on GFX12. */
+#if AMD_LLVM_AVAILABLE
+   if (info->gfx_level == GFX12 && use_llvm && LLVM_VERSION_MAJOR <= 21)
+      options->has_ffmaz_no_denorms = false;
+#else
+   assert(!use_llvm);
+#endif
 }
 
 /* Sleep for the given number of clock cycles. */
diff --git a/src/amd/llvm/ac_nir_to_llvm.c b/src/amd/llvm/ac_nir_to_llvm.c
index 5726b65566e..b66211c1e03 100644
--- a/src/amd/llvm/ac_nir_to_llvm.c
+++ b/src/amd/llvm/ac_nir_to_llvm.c
@@ -767,18 +767,8 @@ static bool visit_alu(struct ac_nir_context *ctx, const nir_alu_instr *instr)
       src[0] = ac_to_float(&ctx->ac, src[0]);
       src[1] = ac_to_float(&ctx->ac, src[1]);
       src[2] = ac_to_float(&ctx->ac, src[2]);
-#if LLVM_VERSION_MAJOR <= 21
-      /* Workaround for LLVM bug that crashes when using legacy fma on GFX12. */
-      if (ctx->ac.gfx_level == GFX12) {
-         LLVMValueRef mulz = ac_build_intrinsic(&ctx->ac, "llvm.amdgcn.fmul.legacy",
-                                                ctx->ac.f32, src, 2, 0);
-         result = LLVMBuildFAdd(ctx->ac.builder, mulz, src[2], "");
-      } else
-#endif
-      {
-         result = ac_build_intrinsic(&ctx->ac, "llvm.amdgcn.fma.legacy", ctx->ac.f32,
-                                     src, 3, 0);
-      }
+      result = ac_build_intrinsic(&ctx->ac, "llvm.amdgcn.fma.legacy", ctx->ac.f32,
+                                  src, 3, 0);
       break;
    case nir_op_ldexp:
       src[0] = ac_to_float(&ctx->ac, src[0]);