The commit has no effect on shaders. The bisecting has most likely been unsuccessful. Setting tile_swizzle = 0 in ac_surface.c reverts the commit.

Note that f7ffa504a065dc2631fd38cc5fe885b277f4e7e7 indeed broke MSAA, but it was fixed by c5c6e0187fd.

The test passes with MESA_GLSL_CACHE_DISABLE=1.

This is odd. As far as I can tell the shader variant produced after loading from the case is the same as the one produced when the cache is disabled.

Its also a fairly simple program. From tests/texturing/shaders/texelFetch.c the offending program is:

    int vs = piglit_compile_shader_text(GL_VERTEX_SHADER,
            "#version 130\n"
            "#extension GL_ARB_explicit_attrib_location: require\n"
            "layout(location=0) in vec4 pos;\n"
            "void main() {\n"
            "   gl_Position = pos;\n"
            "}\n");
    (void)!asprintf(&fs_code,
            "#version 130\n"
            "#extension GL_ARB_explicit_attrib_location: require\n"
            "#extension GL_ARB_fragment_coord_conventions: require\n"
            "uniform int layer;\n"
            "uniform int si;\n"
            "layout(pixel_center_integer) in vec4 gl_FragCoord;\n"
            "layout(location=0) out %s o;\n"
            "void main() {\n"
            "  o = %s(%sgl_FragCoord.x, gl_FragCoord.y, layer, si);\n"
            "}\n",
            sampler.return_type,
            sampler.return_type,
            sampler.data_type == GL_UNSIGNED_INT ? "" : "-");

We must not be setting a flag somewhere, but I've looked over the code that handles the cache multiple  time now and can't spot any real difference between tgsi and nir.

You were right it was a bad bisect due to that patch breaking MSAA also. I found the real issue, fix sent to the list.

https://patchwork.freedesktop.org/patch/288934/

Fixed by:

commit 7536af670b7501228628a8c90f9e8456b5aec9e1
Author: Timothy Arceri <tarceri@itsqueeze.com>
Date:   Wed Feb 27 18:26:07 2019 +1100

    glsl: fix shader cache for packed param list
    
    Some types of params such as some builtins are always padded. We
    need to keep track of this so we can restore the list correctly.
    
    Here we also remove a couple of cache entries that are not actually
    required as they get rebuilt by the _mesa_add_parameter() calls.
    
    This patch fixes a bunch of arb_texture_multisample and
    arb_sample_shading piglit tests for the radeonsi NIR backend.
    
    Fixes: edded1237607 ("mesa: rework ParameterList to allow packing")
    
    Reviewed-by: Marek Olšák <marek.olsak@amd.com>