Parenthesize unary negations to avoid -- (#2087)

* fix(glsl-out,hlsl-out,msl-out): parenthesize unary negations a la `wgsl` everywhere

Unify parenthesization of unary negations across all backends with what the `wgsl` backend does,
which is `<op>(<expr>)`. This avoids ambiguity with output languages for which `--` is a different
operation; in this case, we've been accidentally emitting prefix decrements.

* build: update `rspirv` 0.11 -> 0.12 (FIXME: use upstream release)

* test: add `operators::negation_avoids_prefix_decrement` test

Co-authored-by: Dzmitry Malyshau <kvark@fastmail.com>

Cargo.toml

@@ -73,7 +73,7 @@ diff = "0.1"
 ron = "~0.7.1"
 serde = { version = "1.0", features = ["derive"] }
 spirv = { version = "0.2", features = ["deserialize"] }
-rspirv = "0.11"
+rspirv = { version = "0.11", git = "https://github.com/gfx-rs/rspirv", rev = "b969f175d5663258b4891e44b76c1544da9661ab" }
 env_logger = "0.9"
 
 [workspace]

src/back/glsl/mod.rs

@@ -2519,7 +2519,7 @@ impl<'a, W: Write> Writer<'a, W> {
                             },
                         };
 
-                        write!(self.out, "({}", operator)?;
+                        write!(self.out, "{}(", operator)?;
                     }
                 }
 

src/back/hlsl/writer.rs

@@ -2395,8 +2395,9 @@ impl<'a, W: fmt::Write> super::Writer<'a, W> {
                         }
                     },
                 };
-                write!(self.out, "{}", op_str)?;
+                write!(self.out, "{}(", op_str)?;
                 self.write_expr(module, expr, func_ctx)?;
+                write!(self.out, ")")?;
             }
             Expression::As {
                 expr,

src/back/msl/writer.rs

@@ -1500,8 +1500,9 @@ impl<W: Write> Writer<W> {
                         _ => return Err(Error::Validation),
                     },
                 };
-                write!(self.out, "{}", op_str)?;
+                write!(self.out, "{}(", op_str)?;
                 self.put_expression(expr, context, false)?;
+                write!(self.out, ")")?;
             }
             crate::Expression::Binary { op, left, right } => {
                 let op_str = crate::back::binary_operation_str(op);

tests/in/operators.wgsl

@@ -105,8 +105,6 @@ fn logical() {
 
 fn arithmetic() {
     // unary
-    // TODO: uncomment when we get the changes from https://github.com/gfx-rs/rspirv/pull/231
-    // _ = -1;
     _ = -1.0;
     _ = -vec2(1);
     _ = -vec2(1.0);
@@ -314,3 +312,14 @@ fn main() {
     comparison();
     assignment();
 }
+
+fn negation_avoids_prefix_decrement() {
+    _ = -1;
+    _ = - -2;
+    _ = -(-3);
+    _ = -(- 4);
+    _ = - - -5;
+    _ = - - - - 6;
+    _ = - - -(- -7);
+    _ = (- - - - -8);
+}

tests/out/glsl/operators.main.Compute.glsl

@@ -67,7 +67,7 @@ float constructors() {
 }
 
 void logical() {
-    bool unnamed_11 = (!true);
+    bool unnamed_11 = !(true);
     bvec2 unnamed_12 = not(bvec2(true));
     bool unnamed_13 = (true || false);
     bool unnamed_14 = (true && false);
@@ -78,8 +78,8 @@ void logical() {
 }
 
 void arithmetic() {
-    ivec2 unnamed_19 = (-ivec2(1));
-    vec2 unnamed_20 = (-vec2(1.0));
+    ivec2 unnamed_19 = -(ivec2(1));
+    vec2 unnamed_20 = -(vec2(1.0));
     int unnamed_21 = (2 + 1);
     uint unnamed_22 = (2u + 1u);
     float unnamed_23 = (2.0 + 1.0);
@@ -150,10 +150,10 @@ void arithmetic() {
 }
 
 void bit() {
-    int unnamed_88 = (~1);
-    uint unnamed_89 = (~1u);
-    ivec2 unnamed_90 = (~ivec2(1));
-    uvec3 unnamed_91 = (~uvec3(1u));
+    int unnamed_88 = ~(1);
+    uint unnamed_89 = ~(1u);
+    ivec2 unnamed_90 = ~(ivec2(1));
+    uvec3 unnamed_91 = ~(uvec3(1u));
     int unnamed_92 = (2 | 1);
     uint unnamed_93 = (2u | 1u);
     ivec2 unnamed_94 = (ivec2(2) | ivec2(1));
@@ -251,6 +251,16 @@ void assignment() {
     return;
 }
 
+void negation_avoids_prefix_decrement() {
+    int unnamed_148 = -(-2);
+    int unnamed_149 = -(-3);
+    int unnamed_150 = -(-(4));
+    int unnamed_151 = -(-(-5));
+    int unnamed_152 = -(-(-(-(6))));
+    int unnamed_153 = -(-(-(-(-7))));
+    int unnamed_154 = -(-(-(-(-8))));
+}
+
 void main() {
     vec4 _e4 = builtins();
     vec4 _e5 = splat();

tests/out/hlsl/operators.hlsl

@@ -95,8 +95,8 @@ float constructors()
 
 void logical()
 {
-    bool unnamed_11 = !true;
-    bool2 unnamed_12 = !(true).xx;
+    bool unnamed_11 = !(true);
+    bool2 unnamed_12 = !((true).xx);
     bool unnamed_13 = (true || false);
     bool unnamed_14 = (true && false);
     bool unnamed_15 = (true | false);
@@ -107,8 +107,8 @@ void logical()
 
 void arithmetic()
 {
-    int2 unnamed_19 = -(1).xx;
-    float2 unnamed_20 = -(1.0).xx;
+    int2 unnamed_19 = -((1).xx);
+    float2 unnamed_20 = -((1.0).xx);
     int unnamed_21 = (2 + 1);
     uint unnamed_22 = (2u + 1u);
     float unnamed_23 = (2.0 + 1.0);
@@ -180,10 +180,10 @@ void arithmetic()
 
 void bit()
 {
-    int unnamed_88 = ~1;
-    uint unnamed_89 = ~1u;
-    int2 unnamed_90 = ~(1).xx;
-    uint3 unnamed_91 = ~(1u).xxx;
+    int unnamed_88 = ~(1);
+    uint unnamed_89 = ~(1u);
+    int2 unnamed_90 = ~((1).xx);
+    uint3 unnamed_91 = ~((1u).xxx);
     int unnamed_92 = (2 | 1);
     uint unnamed_93 = (2u | 1u);
     int2 unnamed_94 = ((2).xx | (1).xx);
@@ -284,6 +284,17 @@ void assignment()
     return;
 }
 
+void negation_avoids_prefix_decrement()
+{
+    int unnamed_148 = -(-2);
+    int unnamed_149 = -(-3);
+    int unnamed_150 = -(-(4));
+    int unnamed_151 = -(-(-5));
+    int unnamed_152 = -(-(-(-(6))));
+    int unnamed_153 = -(-(-(-(-7))));
+    int unnamed_154 = -(-(-(-(-8))));
+}
+
 [numthreads(1, 1, 1)]
 void main()
 {

tests/out/msl/operators.msl

@@ -95,8 +95,8 @@ float constructors(
 
 void logical(
 ) {
-    bool unnamed_11 = !true;
-    metal::bool2 unnamed_12 = !metal::bool2(true);
+    bool unnamed_11 = !(true);
+    metal::bool2 unnamed_12 = !(metal::bool2(true));
     bool unnamed_13 = true || false;
     bool unnamed_14 = true && false;
     bool unnamed_15 = true | false;
@@ -107,8 +107,8 @@ void logical(
 
 void arithmetic(
 ) {
-    metal::int2 unnamed_19 = -metal::int2(1);
-    metal::float2 unnamed_20 = -metal::float2(1.0);
+    metal::int2 unnamed_19 = -(metal::int2(1));
+    metal::float2 unnamed_20 = -(metal::float2(1.0));
     int unnamed_21 = 2 + 1;
     uint unnamed_22 = 2u + 1u;
     float unnamed_23 = 2.0 + 1.0;
@@ -180,10 +180,10 @@ void arithmetic(
 
 void bit(
 ) {
-    int unnamed_88 = ~1;
-    uint unnamed_89 = ~1u;
-    metal::int2 unnamed_90 = ~metal::int2(1);
-    metal::uint3 unnamed_91 = ~metal::uint3(1u);
+    int unnamed_88 = ~(1);
+    uint unnamed_89 = ~(1u);
+    metal::int2 unnamed_90 = ~(metal::int2(1));
+    metal::uint3 unnamed_91 = ~(metal::uint3(1u));
     int unnamed_92 = 2 | 1;
     uint unnamed_93 = 2u | 1u;
     metal::int2 unnamed_94 = metal::int2(2) | metal::int2(1);
@@ -283,6 +283,17 @@ void assignment(
     return;
 }
 
+void negation_avoids_prefix_decrement(
+) {
+    int unnamed_148 = -(-2);
+    int unnamed_149 = -(-3);
+    int unnamed_150 = -(-(4));
+    int unnamed_151 = -(-(-5));
+    int unnamed_152 = -(-(-(-(6))));
+    int unnamed_153 = -(-(-(-(-7))));
+    int unnamed_154 = -(-(-(-(-8))));
+}
+
 kernel void main_(
 ) {
     metal::float4 _e4 = builtins();

tests/out/wgsl/operators.wgsl

@@ -251,6 +251,16 @@ fn assignment() {
     return;
 }
 
+fn negation_avoids_prefix_decrement() {
+    _ = -(-2);
+    _ = -(-3);
+    _ = -(-(4));
+    _ = -(-(-5));
+    _ = -(-(-(-(6))));
+    _ = -(-(-(-(-7))));
+    _ = -(-(-(-(-8))));
+}
+
 @compute @workgroup_size(1, 1, 1) 
 fn main() {
     let _e4 = builtins();