From dab6cec1ed78a545c127adc0e8dbdf1f253f9132 Mon Sep 17 00:00:00 2001
From: Anders Leino <aleino@nvidia.com>
Date: Thu, 9 Jan 2025 07:43:31 +0200
Subject: [PATCH] Add parentheses to make precedence explicit (#6030)

* Add parentheses to make precedence explicit

Add parentheses for a few cases that Dawn/Tint (WGSL compiler) complains about.
Closes #6005.

* format code

---------

Co-authored-by: slangbot <186143334+slangbot@users.noreply.github.com>
Co-authored-by: Yong He <yonghe@outlook.com>
---
 source/slang/slang-emit-c-like.cpp            | 28 ++++++++++++
 tests/wgsl/operator-precedence.slang          | 45 +++++++++++++++++++
 .../operator-precedence.slang.expected.txt    | 20 +++++++++
 3 files changed, 93 insertions(+)
 create mode 100644 tests/wgsl/operator-precedence.slang
 create mode 100644 tests/wgsl/operator-precedence.slang.expected.txt

diff --git a/source/slang/slang-emit-c-like.cpp b/source/slang/slang-emit-c-like.cpp
index 64cc9969c4..7ed4d2e4c2 100644
--- a/source/slang/slang-emit-c-like.cpp
+++ b/source/slang/slang-emit-c-like.cpp
@@ -705,6 +705,34 @@ bool CLikeSourceEmitter::maybeEmitParens(EmitOpInfo& outerPrec, const EmitOpInfo
     {
         needParens = true;
     }
+    // a ^ b + c => a ^ (b + c)
+    else if (
+        prec.leftPrecedence == EPrecedence::kEPrecedence_Additive_Left &&
+        outerPrec.leftPrecedence == EPrecedence::kEPrecedence_BitXor_Right)
+    {
+        needParens = true;
+    }
+    // a + b ^ c => (a + b) ^ c
+    else if (
+        prec.rightPrecedence == EPrecedence::kEPrecedence_Additive_Right &&
+        outerPrec.rightPrecedence == EPrecedence::kEPrecedence_BitXor_Left)
+    {
+        needParens = true;
+    }
+    // a | b + c => a | (b + c)
+    else if (
+        prec.leftPrecedence == EPrecedence::kEPrecedence_Additive_Left &&
+        outerPrec.leftPrecedence == EPrecedence::kEPrecedence_BitOr_Right)
+    {
+        needParens = true;
+    }
+    // a + b | c => (a + b) | c
+    else if (
+        prec.rightPrecedence == EPrecedence::kEPrecedence_Additive_Right &&
+        outerPrec.rightPrecedence == EPrecedence::kEPrecedence_BitOr_Left)
+    {
+        needParens = true;
+    }
 
     if (needParens)
     {
diff --git a/tests/wgsl/operator-precedence.slang b/tests/wgsl/operator-precedence.slang
new file mode 100644
index 0000000000..8e90991d67
--- /dev/null
+++ b/tests/wgsl/operator-precedence.slang
@@ -0,0 +1,45 @@
+//TEST(compute):COMPARE_COMPUTE:-shaderobj
+
+//TEST_INPUT:ubuffer(data=[3 7 8], stride=4):name=inputBuffer
+RWStructuredBuffer<uint> inputBuffer;
+
+//TEST_INPUT:ubuffer(data=[0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0], stride=4):out,name=outputBuffer
+RWStructuredBuffer<uint> outputBuffer;
+
+[numthreads(1,1,1)]
+void computeMain()
+{
+    uint a = inputBuffer[0];
+    uint b = inputBuffer[1];
+    uint c = inputBuffer[2];
+
+    outputBuffer[0] = a+b ^ c;
+    outputBuffer[1] = a ^ b+c;
+
+    outputBuffer[2] = a-b | c;
+    outputBuffer[3] = a | b-c;
+
+    outputBuffer[4] = a+b & c;
+    outputBuffer[5] = a & b+c;
+
+    outputBuffer[6] = a<<b ^ c;
+    outputBuffer[7] = a ^ b<<c;
+
+    outputBuffer[8] = a>>b | c;
+    outputBuffer[9] = a | b>>c;
+
+    outputBuffer[10] = a<<b & c;
+    outputBuffer[11] = a & b<<c;
+
+    outputBuffer[12] = a<b && b!=c;
+    outputBuffer[13] = a==b || b>=c;
+
+    outputBuffer[14] = a*b ^ c;
+    outputBuffer[15] = a ^ b*c;
+
+    outputBuffer[16] = a/b | c;
+    outputBuffer[17] = a | b/c;
+
+    outputBuffer[18] = a*b & c;
+    outputBuffer[19] = a & b*c;
+}
diff --git a/tests/wgsl/operator-precedence.slang.expected.txt b/tests/wgsl/operator-precedence.slang.expected.txt
new file mode 100644
index 0000000000..ba2e4b9ab5
--- /dev/null
+++ b/tests/wgsl/operator-precedence.slang.expected.txt
@@ -0,0 +1,20 @@
+2
+C
+FFFFFFFC
+FFFFFFFF
+8
+3
+188
+703
+8
+3
+0
+0
+1
+0
+1D
+3B
+8
+3
+0
+0