ac: fix fast division

This stopped working with LLVM 11 and might occasionally have been broken
on older LLVM, because the metadata was set on the mul, not on the rcp.

Cc: 19.3 20.0 <mesa-stable@lists.freedesktop.org>
Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Tested-by: Marge Bot <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4268>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4268>

diff --git a/src/amd/llvm/ac_llvm_build.c b/src/amd/llvm/ac_llvm_build.c
index dcbd4efeacf2e0755291ff55fcbdf2e141105338..373eb77b4a0c35b1e9126707de98cc200929b9c2 100644 (file)
--- a/src/amd/llvm/ac_llvm_build.c
+++ b/src/amd/llvm/ac_llvm_build.c
@@ -715,12 +715,11 @@ ac_build_fdiv(struct ac_llvm_context *ctx,
         */
        LLVMValueRef one = LLVMConstReal(LLVMTypeOf(num), 1.0);
        LLVMValueRef rcp = LLVMBuildFDiv(ctx->builder, one, den, "");
-       LLVMValueRef ret = LLVMBuildFMul(ctx->builder, num, rcp, "");
-
        /* Use v_rcp_f32 instead of precise division. */
-       if (!LLVMIsConstant(ret))
-               LLVMSetMetadata(ret, ctx->fpmath_md_kind, ctx->fpmath_md_2p5_ulp);
-       return ret;
+       if (!LLVMIsConstant(rcp))
+               LLVMSetMetadata(rcp, ctx->fpmath_md_kind, ctx->fpmath_md_2p5_ulp);
+
+       return LLVMBuildFMul(ctx->builder, num, rcp, "");
 }
 
 /* See fast_idiv_by_const.h. */