[InstCombine][DebugInfo] Remove superflous assertion, add test

[peterwaller-arm]

Summary

When this code was added, an unnecessary assertion slipped in which we
now hit in real code.

Add a test to defend against it firing again.

[paulwalker-arm]

llvm/test/Transforms/InstCombine/debuginfo-scalable-typesize.ll

24

Would it invalid the test if this is changed to ret float %b ?

[peterwaller-arm]

• Use result of the load.

llvm/test/Transforms/InstCombine/debuginfo-scalable-typesize.ll

24

Done.

[peterwaller-arm]

Landed in c4603a8a4384d36d23fd284689b453b9927541be.

[peterwaller-arm]

I erroneously submitted an old version of this patch. Correction in ee7ca88a3ec55a3cd8a81ce54beba12f6b047857.

llvm/lib/Transforms/Utils/Local.cpp

static bool valueCoversEntireFragment(Type *ValTy, DbgVariableIntrinsic *DII) {
   // intead.
   if (DII->isAddressOfVariable()) {
     // DII should have exactly 1 location when it is an address.
     assert(DII->getNumVariableLocationOps() == 1 &&
            "address of variable must have exactly 1 location operand.");
     if (auto *AI =
             dyn_cast_or_null<AllocaInst>(DII->getVariableLocationOp(0))) {
       if (Optional<TypeSize> FragmentSize = AI->getAllocationSizeInBits(DL)) {
-        assert(ValueSize.isScalable() == FragmentSize->isScalable() &&
-               "Both sizes should agree on the scalable flag.");
         return TypeSize::isKnownGE(ValueSize, *FragmentSize);
       }
     }
   }
   // Could not determine size of variable. Conservatively return false.
   return false;
 }
 

llvm/test/Transforms/InstCombine/debuginfo-scalable-typesize.ll

define <vscale x 2 x double> @debug_local_scalable(<vscale x 2 x double> %tostore) {
   call void @llvm.dbg.declare(metadata <vscale x 2 x double>* %vx, metadata !3, metadata !DIExpression()), !dbg !5
   store <vscale x 2 x double> %tostore, <vscale x 2 x double>* %vx, align 16
   %ret = call <vscale x 2 x double> @f(<vscale x 2 x double>* %vx)
   ret <vscale x 2 x double> %ret
 }
 
 declare <vscale x 2 x double> @f(<vscale x 2 x double>*)
 
+define float @debug_scalablevec_bitcast_to_scalar() {
+  %v.addr = alloca <vscale x 4 x float>, align 16
+  call void @llvm.dbg.declare(metadata <vscale x 4 x float>* %v.addr, metadata !3, metadata !DIExpression()), !dbg !5
+  %a = bitcast <vscale x 4 x float>* %v.addr to float*
+  %b = load float, float* %a, align 16
+  ret float %b
+}
+
 declare void @llvm.dbg.declare(metadata, metadata, metadata)
 
 !llvm.module.flags = !{!2}
+!llvm.dbg.cu = !{!0}
 
 !0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1)
 !1 = !DIFile(filename: "/tmp/test.c", directory: "/tmp/")
 !2 = !{i32 2, !"Debug Info Version", i32 3}
 !3 = !DILocalVariable(scope: !4)
 !4 = distinct !DISubprogram(unit: !0)
 !5 = !DILocation(scope: !4)