llvmpipe: Remove the special path for TGSI_OPCODE_EXP.

It was wrong for EXP.y, as we clamped the source before computing the
fractional part, and this opcode should be rarely used, so it's not
worth the hassle.

3 files changed, 30 insertions, 72 deletions

diff --git a/src/gallium/auxiliary/gallivm/lp_bld_arit.c b/src/gallium/auxiliary/gallivm/lp_bld_arit.c
index 09107ff7138..00052ed021f 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_arit.c
+++ b/src/gallium/auxiliary/gallivm/lp_bld_arit.c
@@ -3001,12 +3001,9 @@ const double lp_build_exp2_polynomial[] = {
 };
 
 
-void
-lp_build_exp2_approx(struct lp_build_context *bld,
-                     LLVMValueRef x,
-                     LLVMValueRef *p_exp2_int_part,
-                     LLVMValueRef *p_frac_part,
-                     LLVMValueRef *p_exp2)
+LLVMValueRef
+lp_build_exp2(struct lp_build_context *bld,
+              LLVMValueRef x)
 {
    LLVMBuilderRef builder = bld->gallivm->builder;
    const struct lp_type type = bld->type;
@@ -3019,65 +3016,48 @@ lp_build_exp2_approx(struct lp_build_context *bld,
 
    assert(lp_check_value(bld->type, x));
 
-   if(p_exp2_int_part || p_frac_part || p_exp2) {
-      /* TODO: optimize the constant case */
-      if (gallivm_debug & GALLIVM_DEBUG_PERF &&
-          LLVMIsConstant(x)) {
-         debug_printf("%s: inefficient/imprecise constant arithmetic\n",
-                      __FUNCTION__);
-      }
 
-      assert(type.floating && type.width == 32);
+   /* TODO: optimize the constant case */
+   if (gallivm_debug & GALLIVM_DEBUG_PERF &&
+       LLVMIsConstant(x)) {
+      debug_printf("%s: inefficient/imprecise constant arithmetic\n",
+                   __FUNCTION__);
+   }
 
-      /* We want to preserve NaN and make sure than for exp2 if x > 128,
-       * the result is INF  and if it's smaller than -126.9 the result is 0 */
-      x = lp_build_min_ext(bld, lp_build_const_vec(bld->gallivm, type,  128.0), x,
-                           GALLIVM_NAN_RETURN_SECOND);
-      x = lp_build_max_ext(bld, lp_build_const_vec(bld->gallivm, type, -126.99999), x,
-                           GALLIVM_NAN_RETURN_SECOND);
+   assert(type.floating && type.width == 32);
 
-      /* ipart = floor(x) */
-      /* fpart = x - ipart */
-      lp_build_ifloor_fract(bld, x, &ipart, &fpart);
-   }
+   /* We want to preserve NaN and make sure than for exp2 if x > 128,
+    * the result is INF  and if it's smaller than -126.9 the result is 0 */
+   x = lp_build_min_ext(bld, lp_build_const_vec(bld->gallivm, type,  128.0), x,
+                        GALLIVM_NAN_RETURN_SECOND);
+   x = lp_build_max_ext(bld, lp_build_const_vec(bld->gallivm, type, -126.99999), x,
+                        GALLIVM_NAN_RETURN_SECOND);
 
-   if(p_exp2_int_part || p_exp2) {
-      /* expipart = (float) (1 << ipart) */
-      expipart = LLVMBuildAdd(builder, ipart,
-                              lp_build_const_int_vec(bld->gallivm, type, 127), "");
-      expipart = LLVMBuildShl(builder, expipart,
-                              lp_build_const_int_vec(bld->gallivm, type, 23), "");
-      expipart = LLVMBuildBitCast(builder, expipart, vec_type, "");
-   }
+   /* ipart = floor(x) */
+   /* fpart = x - ipart */
+   lp_build_ifloor_fract(bld, x, &ipart, &fpart);
 
-   if(p_exp2) {
-      expfpart = lp_build_polynomial(bld, fpart, lp_build_exp2_polynomial,
-                                     Elements(lp_build_exp2_polynomial));
 
-      res = LLVMBuildFMul(builder, expipart, expfpart, "");
-   }
 
-   if(p_exp2_int_part)
-      *p_exp2_int_part = expipart;
+   /* expipart = (float) (1 << ipart) */
+   expipart = LLVMBuildAdd(builder, ipart,
+                           lp_build_const_int_vec(bld->gallivm, type, 127), "");
+   expipart = LLVMBuildShl(builder, expipart,
+                           lp_build_const_int_vec(bld->gallivm, type, 23), "");
+   expipart = LLVMBuildBitCast(builder, expipart, vec_type, "");
 
-   if(p_frac_part)
-      *p_frac_part = fpart;
 
-   if(p_exp2)
-      *p_exp2 = res;
-}
+   expfpart = lp_build_polynomial(bld, fpart, lp_build_exp2_polynomial,
+                                  Elements(lp_build_exp2_polynomial));
+
+   res = LLVMBuildFMul(builder, expipart, expfpart, "");
 
 
-LLVMValueRef
-lp_build_exp2(struct lp_build_context *bld,
-              LLVMValueRef x)
-{
-   LLVMValueRef res;
-   lp_build_exp2_approx(bld, x, NULL, NULL, &res);
    return res;
 }
 
 
+
 /**
  * Extract the exponent of a IEEE-754 floating point value.
  *
diff --git a/src/gallium/auxiliary/gallivm/lp_bld_arit.h b/src/gallium/auxiliary/gallivm/lp_bld_arit.h
index d98025e42e3..49d4e2cdc4a 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_arit.h
+++ b/src/gallium/auxiliary/gallivm/lp_bld_arit.h
@@ -326,13 +326,6 @@ lp_build_ilog2(struct lp_build_context *bld,
                LLVMValueRef x);
 
 void
-lp_build_exp2_approx(struct lp_build_context *bld,
-                     LLVMValueRef x,
-                     LLVMValueRef *p_exp2_int_part,
-                     LLVMValueRef *p_frac_part,
-                     LLVMValueRef *p_exp2);
-
-void
 lp_build_log2_approx(struct lp_build_context *bld,
                      LLVMValueRef x,
                      LLVMValueRef *p_exp,
diff --git a/src/gallium/auxiliary/gallivm/lp_bld_tgsi_action.c b/src/gallium/auxiliary/gallivm/lp_bld_tgsi_action.c
index 86c3249575d..1cfaf78853f 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_tgsi_action.c
+++ b/src/gallium/auxiliary/gallivm/lp_bld_tgsi_action.c
@@ -1057,20 +1057,6 @@ ex2_emit_cpu(
                                                         emit_data->args[0]);
 }
 
-/* TGSI_OPCODE_EXP (CPU Only) */
-static void
-exp_emit_cpu(
-   const struct lp_build_tgsi_action * action,
-   struct lp_build_tgsi_context * bld_base,
-   struct lp_build_emit_data * emit_data)
-{
-   lp_build_exp2_approx(&bld_base->base, emit_data->args[0],
-                        &emit_data->output[TGSI_CHAN_X],
-                        &emit_data->output[TGSI_CHAN_Y],
-                        &emit_data->output[TGSI_CHAN_Z]);
-   emit_data->output[TGSI_CHAN_W] = bld_base->base.one;
-}
-
 /* TGSI_OPCODE_F2I (CPU Only) */
 static void
 f2i_emit_cpu(
@@ -1785,7 +1771,6 @@ lp_set_default_actions_cpu(
    bld_base->op_actions[TGSI_OPCODE_CMP].emit = cmp_emit_cpu;
    bld_base->op_actions[TGSI_OPCODE_DIV].emit = div_emit_cpu;
    bld_base->op_actions[TGSI_OPCODE_EX2].emit = ex2_emit_cpu;
-   bld_base->op_actions[TGSI_OPCODE_EXP].emit = exp_emit_cpu;
    bld_base->op_actions[TGSI_OPCODE_F2I].emit = f2i_emit_cpu;
    bld_base->op_actions[TGSI_OPCODE_F2U].emit = f2u_emit_cpu;
    bld_base->op_actions[TGSI_OPCODE_FLR].emit = flr_emit_cpu;