diff --git a/src/back/glsl/mod.rs b/src/back/glsl/mod.rs
index c645ccf9ad..de0d83febf 100644
--- a/src/back/glsl/mod.rs
+++ b/src/back/glsl/mod.rs
@@ -2808,7 +2808,7 @@ impl<'a, W: Write> Writer<'a, W> {
                 // we might need to cast to unsigned integers since
                 // GLSL's findLSB / findMSB always return signed integers
                 let need_extra_paren = {
-                    (fun == Mf::FindLsb || fun == Mf::FindMsb)
+                    (fun == Mf::FindLsb || fun == Mf::FindMsb || fun == Mf::CountOneBits)
                         && match *ctx.info[arg].ty.inner_with(&self.module.types) {
                             crate::TypeInner::Scalar {
                                 kind: crate::ScalarKind::Uint,
diff --git a/src/back/spv/block.rs b/src/back/spv/block.rs
index 1bce7d2719..c4280a7408 100644
--- a/src/back/spv/block.rs
+++ b/src/back/spv/block.rs
@@ -798,10 +798,18 @@ impl<'w> BlockContext<'w> {
                         arg0_id,
                     )),
                     Mf::Determinant => MathOp::Ext(spirv::GLOp::Determinant),
-                    Mf::ReverseBits | Mf::CountOneBits => {
-                        log::error!("unimplemented math function {:?}", fun);
-                        return Err(Error::FeatureNotImplemented("math function"));
-                    }
+                    Mf::ReverseBits => MathOp::Custom(Instruction::unary(
+                        spirv::Op::BitReverse,
+                        result_type_id,
+                        id,
+                        arg0_id,
+                    )),
+                    Mf::CountOneBits => MathOp::Custom(Instruction::unary(
+                        spirv::Op::BitCount,
+                        result_type_id,
+                        id,
+                        arg0_id,
+                    )),
                     Mf::ExtractBits => {
                         let op = match arg_scalar_kind {
                             Some(crate::ScalarKind::Uint) => spirv::Op::BitFieldUExtract,
diff --git a/tests/in/bits.wgsl b/tests/in/bits.wgsl
index 1c78dae201..1e05d81f64 100644
--- a/tests/in/bits.wgsl
+++ b/tests/in/bits.wgsl
@@ -40,4 +40,20 @@ fn main() {
     u2 = firstTrailingBit(u2);
     i3 = firstLeadingBit(i3);
     u = firstLeadingBit(u);
+    i = countOneBits(i);
+    i2 = countOneBits(i2);
+    i3 = countOneBits(i3);
+    i4 = countOneBits(i4);
+    u = countOneBits(u);
+    u2 = countOneBits(u2);
+    u3 = countOneBits(u3);
+    u4 = countOneBits(u4);
+    i = reverseBits(i);
+    i2 = reverseBits(i2);
+    i3 = reverseBits(i3);
+    i4 = reverseBits(i4);
+    u = reverseBits(u);
+    u2 = reverseBits(u2);
+    u3 = reverseBits(u3);
+    u4 = reverseBits(u4);
 }
diff --git a/tests/out/glsl/bits.main.Compute.glsl b/tests/out/glsl/bits.main.Compute.glsl
index 3166d01363..0cdc8906a7 100644
--- a/tests/out/glsl/bits.main.Compute.glsl
+++ b/tests/out/glsl/bits.main.Compute.glsl
@@ -93,6 +93,38 @@ void main() {
     i3_ = findMSB(_e124);
     uint _e126 = u;
     u = uint(findMSB(_e126));
+    int _e128 = i;
+    i = bitCount(_e128);
+    ivec2 _e130 = i2_;
+    i2_ = bitCount(_e130);
+    ivec3 _e132 = i3_;
+    i3_ = bitCount(_e132);
+    ivec4 _e134 = i4_;
+    i4_ = bitCount(_e134);
+    uint _e136 = u;
+    u = uint(bitCount(_e136));
+    uvec2 _e138 = u2_;
+    u2_ = uvec2(bitCount(_e138));
+    uvec3 _e140 = u3_;
+    u3_ = uvec3(bitCount(_e140));
+    uvec4 _e142 = u4_;
+    u4_ = uvec4(bitCount(_e142));
+    int _e144 = i;
+    i = bitfieldReverse(_e144);
+    ivec2 _e146 = i2_;
+    i2_ = bitfieldReverse(_e146);
+    ivec3 _e148 = i3_;
+    i3_ = bitfieldReverse(_e148);
+    ivec4 _e150 = i4_;
+    i4_ = bitfieldReverse(_e150);
+    uint _e152 = u;
+    u = bitfieldReverse(_e152);
+    uvec2 _e154 = u2_;
+    u2_ = bitfieldReverse(_e154);
+    uvec3 _e156 = u3_;
+    u3_ = bitfieldReverse(_e156);
+    uvec4 _e158 = u4_;
+    u4_ = bitfieldReverse(_e158);
     return;
 }
 
diff --git a/tests/out/msl/bits.msl b/tests/out/msl/bits.msl
index 88503320bb..aa35b8c17d 100644
--- a/tests/out/msl/bits.msl
+++ b/tests/out/msl/bits.msl
@@ -93,5 +93,37 @@ kernel void main_(
     i3_ = (((metal::clz(_e124) + 1) % 33) - 1);
     uint _e126 = u;
     u = (((metal::clz(_e126) + 1) % 33) - 1);
+    int _e128 = i;
+    i = metal::popcount(_e128);
+    metal::int2 _e130 = i2_;
+    i2_ = metal::popcount(_e130);
+    metal::int3 _e132 = i3_;
+    i3_ = metal::popcount(_e132);
+    metal::int4 _e134 = i4_;
+    i4_ = metal::popcount(_e134);
+    uint _e136 = u;
+    u = metal::popcount(_e136);
+    metal::uint2 _e138 = u2_;
+    u2_ = metal::popcount(_e138);
+    metal::uint3 _e140 = u3_;
+    u3_ = metal::popcount(_e140);
+    metal::uint4 _e142 = u4_;
+    u4_ = metal::popcount(_e142);
+    int _e144 = i;
+    i = metal::reverse_bits(_e144);
+    metal::int2 _e146 = i2_;
+    i2_ = metal::reverse_bits(_e146);
+    metal::int3 _e148 = i3_;
+    i3_ = metal::reverse_bits(_e148);
+    metal::int4 _e150 = i4_;
+    i4_ = metal::reverse_bits(_e150);
+    uint _e152 = u;
+    u = metal::reverse_bits(_e152);
+    metal::uint2 _e154 = u2_;
+    u2_ = metal::reverse_bits(_e154);
+    metal::uint3 _e156 = u3_;
+    u3_ = metal::reverse_bits(_e156);
+    metal::uint4 _e158 = u4_;
+    u4_ = metal::reverse_bits(_e158);
     return;
 }
diff --git a/tests/out/spv/bits.spvasm b/tests/out/spv/bits.spvasm
index 6d224eee20..ddd71d0b77 100644
--- a/tests/out/spv/bits.spvasm
+++ b/tests/out/spv/bits.spvasm
@@ -1,7 +1,7 @@
 ; SPIR-V
 ; Version: 1.1
 ; Generator: rspirv
-; Bound: 119
+; Bound: 151
 OpCapability Shader
 %1 = OpExtInstImport "GLSL.std.450"
 OpMemoryModel Logical GLSL450
@@ -163,5 +163,53 @@ OpStore %23 %116
 %117 = OpLoad  %6  %27
 %118 = OpExtInst  %6  %1 FindUMsb %117
 OpStore %27 %118
+%119 = OpLoad  %4  %19
+%120 = OpBitCount  %4  %119
+OpStore %19 %120
+%121 = OpLoad  %11  %21
+%122 = OpBitCount  %11  %121
+OpStore %21 %122
+%123 = OpLoad  %12  %23
+%124 = OpBitCount  %12  %123
+OpStore %23 %124
+%125 = OpLoad  %13  %25
+%126 = OpBitCount  %13  %125
+OpStore %25 %126
+%127 = OpLoad  %6  %27
+%128 = OpBitCount  %6  %127
+OpStore %27 %128
+%129 = OpLoad  %14  %29
+%130 = OpBitCount  %14  %129
+OpStore %29 %130
+%131 = OpLoad  %15  %31
+%132 = OpBitCount  %15  %131
+OpStore %31 %132
+%133 = OpLoad  %16  %33
+%134 = OpBitCount  %16  %133
+OpStore %33 %134
+%135 = OpLoad  %4  %19
+%136 = OpBitReverse  %4  %135
+OpStore %19 %136
+%137 = OpLoad  %11  %21
+%138 = OpBitReverse  %11  %137
+OpStore %21 %138
+%139 = OpLoad  %12  %23
+%140 = OpBitReverse  %12  %139
+OpStore %23 %140
+%141 = OpLoad  %13  %25
+%142 = OpBitReverse  %13  %141
+OpStore %25 %142
+%143 = OpLoad  %6  %27
+%144 = OpBitReverse  %6  %143
+OpStore %27 %144
+%145 = OpLoad  %14  %29
+%146 = OpBitReverse  %14  %145
+OpStore %29 %146
+%147 = OpLoad  %15  %31
+%148 = OpBitReverse  %15  %147
+OpStore %31 %148
+%149 = OpLoad  %16  %33
+%150 = OpBitReverse  %16  %149
+OpStore %33 %150
 OpReturn
 OpFunctionEnd
\ No newline at end of file
diff --git a/tests/out/wgsl/bits.wgsl b/tests/out/wgsl/bits.wgsl
index 2bdaf6e9ff..ccaebff41e 100644
--- a/tests/out/wgsl/bits.wgsl
+++ b/tests/out/wgsl/bits.wgsl
@@ -87,5 +87,37 @@ fn main() {
     i3_ = firstLeadingBit(_e124);
     let _e126 = u;
     u = firstLeadingBit(_e126);
+    let _e128 = i;
+    i = countOneBits(_e128);
+    let _e130 = i2_;
+    i2_ = countOneBits(_e130);
+    let _e132 = i3_;
+    i3_ = countOneBits(_e132);
+    let _e134 = i4_;
+    i4_ = countOneBits(_e134);
+    let _e136 = u;
+    u = countOneBits(_e136);
+    let _e138 = u2_;
+    u2_ = countOneBits(_e138);
+    let _e140 = u3_;
+    u3_ = countOneBits(_e140);
+    let _e142 = u4_;
+    u4_ = countOneBits(_e142);
+    let _e144 = i;
+    i = reverseBits(_e144);
+    let _e146 = i2_;
+    i2_ = reverseBits(_e146);
+    let _e148 = i3_;
+    i3_ = reverseBits(_e148);
+    let _e150 = i4_;
+    i4_ = reverseBits(_e150);
+    let _e152 = u;
+    u = reverseBits(_e152);
+    let _e154 = u2_;
+    u2_ = reverseBits(_e154);
+    let _e156 = u3_;
+    u3_ = reverseBits(_e156);
+    let _e158 = u4_;
+    u4_ = reverseBits(_e158);
     return;
 }