Case handling MachineOperandType address of a global value in SIFoldOperands

[isakhilesh]

While FoldingImmLike accepts MO_Immediate, MO_FrameIndex and MO_GlobalAddress, the conditional block after it only covers the first 2, so I have added a case for the global value as well.

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[llvmbot]

@llvm/pr-subscribers-clang

Author: Akhilesh Moorthy (isakhilesh)

Changes

While FoldingImmLike accepts MO_Immediate, MO_FrameIndex and MO_GlobalAddress, the conditional block after it only covers the first 2, so I have added a case for the global value as well.

---

Full diff: https://github.com/llvm/llvm-project/pull/135404.diff

2 Files Affected:

• (modified) clang/include/clang/Basic/AttrDocs.td (+5-3)
• (modified) llvm/lib/Target/AMDGPU/SIFoldOperands.cpp (+3-1)

diff --git a/clang/include/clang/Basic/AttrDocs.td b/clang/include/clang/Basic/AttrDocs.td
index c8b371280e35d..97a5f24d35d7d 100644
--- a/clang/include/clang/Basic/AttrDocs.td
+++ b/clang/include/clang/Basic/AttrDocs.td
@@ -7517,9 +7517,11 @@ the field it is attached to, and it may also lead to emission of automatic fix-i
 hints which would help the user replace the use of unsafe functions(/fields) with safe
 alternatives, though the attribute can be used even when the fix can't be automated.
 
-* Attribute attached to functions: The attribute does not suppress
-  ``-Wunsafe-buffer-usage`` inside the function to which it is attached.
-  These warnings still need to be addressed.
+* Attribute attached to functions: The attribute suppresses all
+  ``-Wunsafe-buffer-usage`` warnings within the function it is attached to, as the
+  function is now classified as unsafe. The attribute should be used carefully, as it
+  will silence all unsafe operation warnings inside the function; including any new
+  unsafe operations introduced in the future.
 
   The attribute is warranted even if the only way a function can overflow
   the buffer is by violating the function's preconditions. For example, it
diff --git a/llvm/lib/Target/AMDGPU/SIFoldOperands.cpp b/llvm/lib/Target/AMDGPU/SIFoldOperands.cpp
index d6acf9e081b9f..701d17930d7df 100644
--- a/llvm/lib/Target/AMDGPU/SIFoldOperands.cpp
+++ b/llvm/lib/Target/AMDGPU/SIFoldOperands.cpp
@@ -1161,8 +1161,10 @@ void SIFoldOperandsImpl::foldOperand(
 
         if (OpToFold.isImm())
           UseMI->getOperand(1).ChangeToImmediate(OpToFold.getImm());
-        else
+        else if(OpToFold.isFI())
           UseMI->getOperand(1).ChangeToFrameIndex(OpToFold.getIndex());
+        else if(OpToFold.isGlobal())
+          return;
         UseMI->removeOperand(2); // Remove exec read (or src1 for readlane)
         return;
       }

[llvmbot]

@llvm/pr-subscribers-backend-amdgpu

Author: Akhilesh Moorthy (isakhilesh)

Changes

While FoldingImmLike accepts MO_Immediate, MO_FrameIndex and MO_GlobalAddress, the conditional block after it only covers the first 2, so I have added a case for the global value as well.

---

Full diff: https://github.com/llvm/llvm-project/pull/135404.diff

2 Files Affected:

• (modified) clang/include/clang/Basic/AttrDocs.td (+5-3)
• (modified) llvm/lib/Target/AMDGPU/SIFoldOperands.cpp (+3-1)

diff --git a/clang/include/clang/Basic/AttrDocs.td b/clang/include/clang/Basic/AttrDocs.td
index c8b371280e35d..97a5f24d35d7d 100644
--- a/clang/include/clang/Basic/AttrDocs.td
+++ b/clang/include/clang/Basic/AttrDocs.td
@@ -7517,9 +7517,11 @@ the field it is attached to, and it may also lead to emission of automatic fix-i
 hints which would help the user replace the use of unsafe functions(/fields) with safe
 alternatives, though the attribute can be used even when the fix can't be automated.
 
-* Attribute attached to functions: The attribute does not suppress
-  ``-Wunsafe-buffer-usage`` inside the function to which it is attached.
-  These warnings still need to be addressed.
+* Attribute attached to functions: The attribute suppresses all
+  ``-Wunsafe-buffer-usage`` warnings within the function it is attached to, as the
+  function is now classified as unsafe. The attribute should be used carefully, as it
+  will silence all unsafe operation warnings inside the function; including any new
+  unsafe operations introduced in the future.
 
   The attribute is warranted even if the only way a function can overflow
   the buffer is by violating the function's preconditions. For example, it
diff --git a/llvm/lib/Target/AMDGPU/SIFoldOperands.cpp b/llvm/lib/Target/AMDGPU/SIFoldOperands.cpp
index d6acf9e081b9f..701d17930d7df 100644
--- a/llvm/lib/Target/AMDGPU/SIFoldOperands.cpp
+++ b/llvm/lib/Target/AMDGPU/SIFoldOperands.cpp
@@ -1161,8 +1161,10 @@ void SIFoldOperandsImpl::foldOperand(
 
         if (OpToFold.isImm())
           UseMI->getOperand(1).ChangeToImmediate(OpToFold.getImm());
-        else
+        else if(OpToFold.isFI())
           UseMI->getOperand(1).ChangeToFrameIndex(OpToFold.getIndex());
+        else if(OpToFold.isGlobal())
+          return;
         UseMI->removeOperand(2); // Remove exec read (or src1 for readlane)
         return;
       }