[Mesa-dev] [PATCH 6/9] glsl: Fix undefined shifts.

[Ian Romanick]

On 01/11/2016 02:48 PM, Matt Turner wrote:
> Shifting into the sign bit if undefined, as is shifting by 32.
> 
> Reviewed-by: Jordan Justen <jordan.l.justen at intel.com>
> ---
>  src/glsl/ir_constant_expression.cpp | 8 ++++----
>  src/glsl/nir/nir_opcodes.py         | 6 +++---
>  2 files changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/src/glsl/ir_constant_expression.cpp b/src/glsl/ir_constant_expression.cpp
> index 7613139..77828bf 100644
> --- a/src/glsl/ir_constant_expression.cpp
> +++ b/src/glsl/ir_constant_expression.cpp
> @@ -1539,10 +1539,10 @@ ir_expression::constant_expression_value(struct hash_table *variable_context)
>              data.i[c] = -1;
>           else {
>              int count = 0;
> -            int top_bit = op[0]->type->base_type == GLSL_TYPE_UINT
> -                          ? 0 : v & (1 << 31);
> +            unsigned top_bit = op[0]->type->base_type == GLSL_TYPE_UINT

const?  Either way, this patch is

Reviewed-by: Ian Romanick <ian.d.romanick at intel.com>

> +                               ? 0 : v & (1u << 31);
>  
> -            while (((v & (1 << 31)) == top_bit) && count != 32) {
> +            while (((v & (1u << 31)) == top_bit) && count != 32) {
>                 count++;
>                 v <<= 1;
>              }
> @@ -1721,7 +1721,7 @@ ir_expression::constant_expression_value(struct hash_table *variable_context)
>           else if (offset + bits > 32)
>              data.u[c] = 0; /* Undefined, per spec. */
>           else {
> -            unsigned insert_mask = ((1 << bits) - 1) << offset;
> +            unsigned insert_mask = ((1ul << bits) - 1) << offset;
>  
>              unsigned insert = op[1]->value.u[c];
>              insert <<= offset;
> diff --git a/src/glsl/nir/nir_opcodes.py b/src/glsl/nir/nir_opcodes.py
> index 855095f..9e92fab 100644
> --- a/src/glsl/nir/nir_opcodes.py
> +++ b/src/glsl/nir/nir_opcodes.py
> @@ -516,7 +516,7 @@ int bits = src0, offset = src1;
>  if (offset < 0 || bits < 0 || offset + bits > 32)
>     dst = 0; /* undefined per the spec */
>  else
> -   dst = ((1 << bits)- 1) << offset;
> +   dst = ((1ul << bits) - 1) << offset;
>  """)
>  
>  opcode("ldexp", 0, tfloat, [0, 0], [tfloat, tint], "", """
> @@ -578,7 +578,7 @@ if (bits == 0) {
>  } else if (bits < 0 || offset < 0 || offset + bits > 32) {
>     dst = 0; /* undefined per the spec */
>  } else {
> -   dst = (base >> offset) & ((1 << bits) - 1);
> +   dst = (base >> offset) & ((1ul << bits) - 1);
>  }
>  """)
>  opcode("ibitfield_extract", 0, tint,
> @@ -618,7 +618,7 @@ if (bits == 0) {
>  } else if (offset < 0 || bits < 0 || bits + offset > 32) {
>     dst = 0;
>  } else {
> -   unsigned mask = ((1 << bits) - 1) << offset;
> +   unsigned mask = ((1ul << bits) - 1) << offset;
>     dst = (base & ~mask) | ((insert << bits) & mask);
>  }
>  """)
>