gallivm: Generalize lp_build_mul and lp_build_lerp for signed normalized types.

This fixes fdo bug 57755 and most of the failures of piglit fbo-blending-formats
GL_EXT_texture_snorm.

GL_INTENSITY_SNORM is still failing, but problem is probably elsewhere,
as GL_R8_SNORM works fine.

1 files changed, 82 insertions, 92 deletions

diff --git a/src/gallium/auxiliary/gallivm/lp_bld_arit.c b/src/gallium/auxiliary/gallivm/lp_bld_arit.c
index 33b8f6dc9fe..4c6fd9ef7ca 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_arit.c
+++ b/src/gallium/auxiliary/gallivm/lp_bld_arit.c
@@ -45,6 +45,8 @@
  */
 
 
+#include <float.h>
+
 #include "util/u_memory.h"
 #include "util/u_debug.h"
 #include "util/u_math.h"
@@ -58,9 +60,9 @@
 #include "lp_bld_logic.h"
 #include "lp_bld_pack.h"
 #include "lp_bld_debug.h"
+#include "lp_bld_bitarit.h"
 #include "lp_bld_arit.h"
 
-#include "float.h"
 
 #define EXP_POLY_DEGREE 5
 
@@ -679,8 +681,12 @@ lp_build_sub(struct lp_build_context *bld,
 }
 
 
+
 /**
- * Normalized 8bit multiplication.
+ * Normalized multiplication.
+ *
+ * There are several approaches here (using 8-bit normalized multiplication as
+ * an example):
  *
  * - alpha plus one
  *
@@ -721,66 +727,56 @@ lp_build_sub(struct lp_build_context *bld,
  *     http://www.stereopsis.com/doubleblend.html
  */
 static LLVMValueRef
-lp_build_mul_u8n(struct gallivm_state *gallivm,
-                 struct lp_type i16_type,
-                 LLVMValueRef a, LLVMValueRef b)
+lp_build_mul_norm(struct gallivm_state *gallivm,
+                  struct lp_type wide_type,
+                  LLVMValueRef a, LLVMValueRef b)
 {
    LLVMBuilderRef builder = gallivm->builder;
-   LLVMValueRef c8;
+   struct lp_build_context bld;
+   unsigned bits;
+   LLVMValueRef shift;
+   LLVMValueRef half;
    LLVMValueRef ab;
 
-   assert(!i16_type.floating);
-   assert(lp_check_value(i16_type, a));
-   assert(lp_check_value(i16_type, b));
+   assert(!wide_type.floating);
+   assert(lp_check_value(wide_type, a));
+   assert(lp_check_value(wide_type, b));
+
+   lp_build_context_init(&bld, gallivm, wide_type);
+
+   bits = wide_type.width / 2;
+   if (wide_type.sign) {
+      --bits;
+   }
+
+   shift = lp_build_const_int_vec(gallivm, wide_type, bits);
 
-   c8 = lp_build_const_int_vec(gallivm, i16_type, 8);
-   
 #if 0
    
    /* a*b/255 ~= (a*(b + 1)) >> 256 */
-   b = LLVMBuildAdd(builder, b, lp_build_const_int_vec(gallium, i16_type, 1), "");
+   /* XXX: This would not work for signed types */
+   assert(!wide_type.sign);
+   b = LLVMBuildAdd(builder, b, lp_build_const_int_vec(gallium, wide_type, 1), "");
    ab = LLVMBuildMul(builder, a, b, "");
 
 #else
    
    /* ab/255 ~= (ab + (ab >> 8) + 0x80) >> 8 */
    ab = LLVMBuildMul(builder, a, b, "");
-   ab = LLVMBuildAdd(builder, ab, LLVMBuildLShr(builder, ab, c8, ""), "");
-   ab = LLVMBuildAdd(builder, ab, lp_build_const_int_vec(gallivm, i16_type, 0x80), "");
+   ab = LLVMBuildAdd(builder, ab, LLVMBuildLShr(builder, ab, shift, ""), "");
+
+   /* Add rounding term */
+   half = lp_build_const_int_vec(gallivm, wide_type, 1 << (bits - 1));
+   if (wide_type.sign) {
+      LLVMValueRef minus_half = LLVMBuildNeg(builder, half, "");
+      LLVMValueRef sign = lp_build_shr_imm(&bld, half, wide_type.width - 1);
+      half = lp_build_select(&bld, sign, minus_half, half);
+   }
+   ab = LLVMBuildAdd(builder, ab, half, "");
 
 #endif
    
-   ab = LLVMBuildLShr(builder, ab, c8, "");
-
-   return ab;
-}
-
-/**
- * Normalized 16bit multiplication.
- *
- * Utilises same principle as above code.
- */
-static LLVMValueRef
-lp_build_mul_u16n(struct gallivm_state *gallivm,
-                 struct lp_type i32_type,
-                 LLVMValueRef a, LLVMValueRef b)
-{
-   LLVMBuilderRef builder = gallivm->builder;
-   LLVMValueRef c16;
-   LLVMValueRef ab;
-
-   assert(!i32_type.floating);
-   assert(lp_check_value(i32_type, a));
-   assert(lp_check_value(i32_type, b));
-
-   c16 = lp_build_const_int_vec(gallivm, i32_type, 16);
-
-   /* ab/65535 ~= (ab + (ab >> 16) + 0x8000) >> 16 */
-   ab = LLVMBuildMul(builder, a, b, "");
-   ab = LLVMBuildAdd(builder, ab, LLVMBuildLShr(builder, ab, c16, ""), "");
-   ab = LLVMBuildAdd(builder, ab, lp_build_const_int_vec(gallivm, i32_type, 0x8000), "");
-
-   ab = LLVMBuildLShr(builder, ab, c16, "");
+   ab = LLVMBuildLShr(builder, ab, shift, "");
 
    return ab;
 }
@@ -812,41 +808,20 @@ lp_build_mul(struct lp_build_context *bld,
    if(a == bld->undef || b == bld->undef)
       return bld->undef;
 
-   if(!type.floating && !type.fixed && type.norm) {
-      if(type.width == 8) {
-         struct lp_type i16_type = lp_wider_type(type);
-         LLVMValueRef al, ah, bl, bh, abl, abh, ab;
-
-         lp_build_unpack2(bld->gallivm, type, i16_type, a, &al, &ah);
-         lp_build_unpack2(bld->gallivm, type, i16_type, b, &bl, &bh);
-
-         /* PMULLW, PSRLW, PADDW */
-         abl = lp_build_mul_u8n(bld->gallivm, i16_type, al, bl);
-         abh = lp_build_mul_u8n(bld->gallivm, i16_type, ah, bh);
-
-         ab = lp_build_pack2(bld->gallivm, i16_type, type, abl, abh);
-         
-         return ab;
-      }
-
-      if(type.width == 16) {
-         struct lp_type i32_type = lp_wider_type(type);
-         LLVMValueRef al, ah, bl, bh, abl, abh, ab;
+   if (!type.floating && !type.fixed && type.norm) {
+      struct lp_type wide_type = lp_wider_type(type);
+      LLVMValueRef al, ah, bl, bh, abl, abh, ab;
 
-         lp_build_unpack2(bld->gallivm, type, i32_type, a, &al, &ah);
-         lp_build_unpack2(bld->gallivm, type, i32_type, b, &bl, &bh);
+      lp_build_unpack2(bld->gallivm, type, wide_type, a, &al, &ah);
+      lp_build_unpack2(bld->gallivm, type, wide_type, b, &bl, &bh);
 
-         /* PMULLW, PSRLW, PADDW */
-         abl = lp_build_mul_u16n(bld->gallivm, i32_type, al, bl);
-         abh = lp_build_mul_u16n(bld->gallivm, i32_type, ah, bh);
+      /* PMULLW, PSRLW, PADDW */
+      abl = lp_build_mul_norm(bld->gallivm, wide_type, al, bl);
+      abh = lp_build_mul_norm(bld->gallivm, wide_type, ah, bh);
 
-         ab = lp_build_pack2(bld->gallivm, i32_type, type, abl, abh);
+      ab = lp_build_pack2(bld->gallivm, wide_type, type, abl, abh);
 
-         return ab;
-      }
-
-      /* FIXME */
-      assert(0);
+      return ab;
    }
 
    if(type.fixed)
@@ -988,7 +963,10 @@ lp_build_div(struct lp_build_context *bld,
 
 
 /**
- * Linear interpolation -- without any checks.
+ * Linear interpolation helper.
+ *
+ * @param normalized whether we are interpolating normalized values,
+ *        encoded in normalized integers, twice as wide.
  *
  * @sa http://www.stereopsis.com/doubleblend.html
  */
@@ -996,8 +974,10 @@ static INLINE LLVMValueRef
 lp_build_lerp_simple(struct lp_build_context *bld,
                      LLVMValueRef x,
                      LLVMValueRef v0,
-                     LLVMValueRef v1)
+                     LLVMValueRef v1,
+                     bool normalized)
 {
+   unsigned half_width = bld->type.width/2;
    LLVMBuilderRef builder = bld->gallivm->builder;
    LLVMValueRef delta;
    LLVMValueRef res;
@@ -1010,14 +990,19 @@ lp_build_lerp_simple(struct lp_build_context *bld,
 
    res = lp_build_mul(bld, x, delta);
 
+   if (normalized) {
+      if (bld->type.sign) {
+         res = lp_build_shr_imm(bld, res, half_width - 1);
+      } else {
+         res = lp_build_shr_imm(bld, res, half_width);
+      }
+   }
+
    res = lp_build_add(bld, v0, res);
 
-   if (bld->type.fixed) {
-      /* XXX: This step is necessary for lerping 8bit colors stored on 16bits,
-       * but it will be wrong for other uses. Basically we need a more
-       * powerful lp_type, capable of further distinguishing the values
-       * interpretation from the value storage. */
-      res = LLVMBuildAnd(builder, res, lp_build_const_int_vec(bld->gallivm, bld->type, (1 << bld->type.width/2) - 1), "");
+   if (normalized && !bld->type.sign) {
+      /* We need to mask out the high order bits when lerping 8bit normalized colors stored on 16bits */
+      res = LLVMBuildAnd(builder, res, lp_build_const_int_vec(bld->gallivm, bld->type, (1 << half_width) - 1), "");
    }
 
    return res;
@@ -1045,17 +1030,17 @@ lp_build_lerp(struct lp_build_context *bld,
       struct lp_type wide_type;
       struct lp_build_context wide_bld;
       LLVMValueRef xl, xh, v0l, v0h, v1l, v1h, resl, resh;
+      unsigned bits;
       LLVMValueRef shift;
 
       assert(type.length >= 2);
-      assert(!type.sign);
 
       /*
-       * Create a wider type, enough to hold the intermediate result of the
-       * multiplication.
+       * Create a wider integer type, enough to hold the
+       * intermediate result of the multiplication.
        */
       memset(&wide_type, 0, sizeof wide_type);
-      wide_type.fixed  = TRUE;
+      wide_type.sign   = type.sign;
       wide_type.width  = type.width*2;
       wide_type.length = type.length/2;
 
@@ -1069,7 +1054,12 @@ lp_build_lerp(struct lp_build_context *bld,
        * Scale x from [0, 255] to [0, 256]
        */
 
-      shift = lp_build_const_int_vec(bld->gallivm, wide_type, type.width - 1);
+      bits = type.width - 1;
+      if (type.sign) {
+         --bits;
+      }
+
+      shift = lp_build_const_int_vec(bld->gallivm, wide_type, bits - 1);
 
       xl = lp_build_add(&wide_bld, xl,
                         LLVMBuildAShr(builder, xl, shift, ""));
@@ -1080,12 +1070,12 @@ lp_build_lerp(struct lp_build_context *bld,
        * Lerp both halves.
        */
 
-      resl = lp_build_lerp_simple(&wide_bld, xl, v0l, v1l);
-      resh = lp_build_lerp_simple(&wide_bld, xh, v0h, v1h);
+      resl = lp_build_lerp_simple(&wide_bld, xl, v0l, v1l, TRUE);
+      resh = lp_build_lerp_simple(&wide_bld, xh, v0h, v1h, TRUE);
 
       res = lp_build_pack2(bld->gallivm, wide_type, type, resl, resh);
    } else {
-      res = lp_build_lerp_simple(bld, x, v0, v1);
+      res = lp_build_lerp_simple(bld, x, v0, v1, FALSE);
    }
 
    return res;