IR: Add immarg attribute

This indicates an intrinsic parameter is required to be a constant,
and should not be replaced with a non-constant value.

Add the attribute to all AMDGPU and generic intrinsics that comments
indicate it should apply to. I scanned other target intrinsics, but I
don't see any obvious comments indicating which arguments are intended
to be only immediates.

This breaks one questionable testcase for the autoupgrade. I'm unclear
on whether the autoupgrade is supposed to really handle declarations
which were never valid. The verifier fails because the attributes now
refer to a parameter past the end of the argument list.

llvm-svn: 355981

1 files changed, 4 insertions, 10 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
index 6f9aadea55d..8e97da68819 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
@@ -982,10 +982,7 @@ Value *InstCombiner::simplifyAMDGCNMemoryIntrinsicDemanded(IntrinsicInst *II,
     // below.
     DemandedElts = (1 << DemandedElts.getActiveBits()) - 1;
   } else {
-    ConstantInt *DMask = dyn_cast<ConstantInt>(II->getArgOperand(DMaskIdx));
-    if (!DMask)
-      return nullptr; // non-constant dmask is not supported by codegen
-
+    ConstantInt *DMask = cast<ConstantInt>(II->getArgOperand(DMaskIdx));
     unsigned DMaskVal = DMask->getZExtValue() & 0xf;
 
     // Mask off values that are undefined because the dmask doesn't cover them
@@ -1639,12 +1636,9 @@ Value *InstCombiner::SimplifyDemandedVectorElts(Value *V, APInt DemandedElts,
       return simplifyAMDGCNMemoryIntrinsicDemanded(II, DemandedElts);
     default: {
       if (getAMDGPUImageDMaskIntrinsic(II->getIntrinsicID())) {
-        LLVM_DEBUG(
-          Value *TFC = II->getArgOperand(II->getNumOperands() - 2);
-          assert(!isa<ConstantInt>(TFC) ||
-                 dyn_cast<ConstantInt>(TFC)->getZExtValue() == 0);
-        );
-
+        assert(cast<ConstantInt>(
+                 II->getArgOperand(
+                   II->getNumOperands() - 2))->getZExtValue() == 0);
         return simplifyAMDGCNMemoryIntrinsicDemanded(II, DemandedElts, 0);
       }