[IR] Forbid mixing condition and operand bundle assumes (#160460)

Assumes either have a boolean condition, or a number of attribute based
operand bundles. Currently, we also allow mixing both forms, though we
don't make use of this in practice. This adds additional complexity for
code dealing with assumes.

Forbid mixing both forms, by requiring that assumes with operand bundles
have an i1 true condition.

Author: nikic

llvm/docs/LangRef.rst

@@ -3013,6 +3013,8 @@ assumptions, such as that a :ref:`parameter attribute <paramattrs>` or a
 location. Operand bundles enable assumptions that are either hard or impossible
 to represent as a boolean argument of an :ref:`llvm.assume <int_assume>`.
 
+Assumes with operand bundles must have ``i1 true`` as the condition operand.
+
 An assume operand bundle has the form:
 
 ::
@@ -3045,7 +3047,7 @@ allows the optimizer to assume that at location of call to
 
 .. code-block:: llvm
 
-      call void @llvm.assume(i1 %cond) ["cold"(), "nonnull"(ptr %val)]
+      call void @llvm.assume(i1 true) ["cold"(), "nonnull"(ptr %val)]
 
 allows the optimizer to assume that the :ref:`llvm.assume <int_assume>`
 call location is cold and that ``%val`` may not be null.

llvm/lib/IR/Verifier.cpp

@@ -5675,6 +5675,11 @@ void Verifier::visitIntrinsicCall(Intrinsic::ID ID, CallBase &Call) {
   default:
     break;
   case Intrinsic::assume: {
+    if (Call.hasOperandBundles()) {
+      auto *Cond = dyn_cast<ConstantInt>(Call.getArgOperand(0));
+      Check(Cond && Cond->isOne(),
+            "assume with operand bundles must have i1 true condition", Call);
+    }
     for (auto &Elem : Call.bundle_op_infos()) {
       unsigned ArgCount = Elem.End - Elem.Begin;
       // Separate storage assumptions are special insofar as they're the only

llvm/test/Transforms/AlignmentFromAssumptions/domtree-crash.ll

@@ -9,10 +9,10 @@
 
 define void @fn1() {
 ; CHECK-LABEL: define void @fn1() {
-; CHECK-NEXT:    call void @llvm.assume(i1 false) [ "align"(ptr @global, i64 1) ]
+; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "align"(ptr @global, i64 1) ]
 ; CHECK-NEXT:    ret void
 ;
-  call void @llvm.assume(i1 false) [ "align"(ptr @global, i64 1) ]
+  call void @llvm.assume(i1 true) [ "align"(ptr @global, i64 1) ]
   ret void
 }
 

llvm/test/Transforms/InstCombine/assume.ll

@@ -498,24 +498,24 @@ not_taken:
 define i1 @nonnull3B(ptr %a, i1 %control) {
 ; CHECK-LABEL: @nonnull3B(
 ; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[LOAD:%.*]] = load ptr, ptr [[A:%.*]], align 8
 ; CHECK-NEXT:    br i1 [[CONTROL:%.*]], label [[TAKEN:%.*]], label [[NOT_TAKEN:%.*]]
 ; CHECK:       taken:
-; CHECK-NEXT:    [[LOAD:%.*]] = load ptr, ptr [[A:%.*]], align 8
-; CHECK-NEXT:    [[CMP:%.*]] = icmp ne ptr [[LOAD]], null
-; CHECK-NEXT:    call void @llvm.assume(i1 [[CMP]]) [ "nonnull"(ptr [[LOAD]]) ]
-; CHECK-NEXT:    ret i1 [[CMP]]
+; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "nonnull"(ptr [[LOAD]]) ]
+; CHECK-NEXT:    ret i1 true
 ; CHECK:       not_taken:
+; CHECK-NEXT:    call void @llvm.assume(i1 true) [ "nonnull"(ptr [[LOAD]]) ]
 ; CHECK-NEXT:    ret i1 false
 ;
 entry:
   %load = load ptr, ptr %a
   %cmp = icmp ne ptr %load, null
   br i1 %control, label %taken, label %not_taken
 taken:
-  call void @llvm.assume(i1 %cmp) ["nonnull"(ptr %load)]
+  call void @llvm.assume(i1 true) ["nonnull"(ptr %load)]
   ret i1 %cmp
 not_taken:
-  call void @llvm.assume(i1 %cmp) ["nonnull"(ptr %load)]
+  call void @llvm.assume(i1 true) ["nonnull"(ptr %load)]
   ret i1 %control
 }
 
@@ -544,7 +544,7 @@ taken:
   br label %exit
 exit:
   ; FIXME: this shouldn't be dropped because it is still dominated by the new position of %load
-  call void @llvm.assume(i1 %cmp) ["nonnull"(ptr %load)]
+  call void @llvm.assume(i1 %cmp)
   ret i1 %cmp2
 not_taken:
   call void @llvm.assume(i1 %cmp)
@@ -575,7 +575,7 @@ taken:
 exit:
   ret i1 %cmp2
 not_taken:
-  call void @llvm.assume(i1 %cmp) ["nonnull"(ptr %load)]
+  call void @llvm.assume(i1 %cmp)
   ret i1 %control
 }
 

llvm/test/Verifier/assume-bundles.ll

@@ -3,7 +3,7 @@
 
 declare void @llvm.assume(i1)
 
-define void @func(ptr %P, i32 %P1, ptr %P2, ptr %P3) {
+define void @func(ptr %P, i32 %P1, ptr %P2, ptr %P3, i1 %cond) {
 ; CHECK: tags must be valid attribute names
 ; CHECK: "adazdazd"
   call void @llvm.assume(i1 true) ["adazdazd"()]
@@ -32,5 +32,7 @@ define void @func(ptr %P, i32 %P1, ptr %P2, ptr %P3) {
   call void @llvm.assume(i1 true) ["separate_storage"(ptr %P, i32 123)]
 ; CHECK: dereferenceable assumptions should have 2 arguments
   call void @llvm.assume(i1 true) ["align"(ptr %P, i32 4), "dereferenceable"(ptr %P)]
+; CHECK: assume with operand bundles must have i1 true condition
+  call void @llvm.assume(i1 %cond) ["nonnull"(ptr %P)]
   ret void
 }

mlir/test/Target/LLVMIR/Import/intrinsic.ll

@@ -733,12 +733,12 @@ define void @assume(i1 %true) {
 }
 
 ; CHECK-LABEL: @assume_with_opbundles
-; CHECK-SAME:  %[[TRUE:[a-zA-Z0-9]+]]
 ; CHECK-SAME:  %[[PTR:[a-zA-Z0-9]+]]
-define void @assume_with_opbundles(i1 %true, ptr %p) {
+define void @assume_with_opbundles(ptr %p) {
+  ; CHECK: %[[TRUE:.+]] = llvm.mlir.constant(true) : i1
   ; CHECK: %[[ALIGN:.+]] = llvm.mlir.constant(8 : i32) : i32
   ; CHECK:  llvm.intr.assume %[[TRUE]] ["align"(%[[PTR]], %[[ALIGN]] : !llvm.ptr, i32)] : i1
-  call void @llvm.assume(i1 %true) ["align"(ptr %p, i32 8)]
+  call void @llvm.assume(i1 true) ["align"(ptr %p, i32 8)]
   ret void
 }
 

mlir/test/Target/LLVMIR/llvmir-intrinsics.mlir

@@ -460,10 +460,11 @@ llvm.func @assume_without_opbundles(%cond: i1) {
 }
 
 // CHECK-LABEL: @assume_with_opbundles
-llvm.func @assume_with_opbundles(%cond: i1, %p: !llvm.ptr) {
+llvm.func @assume_with_opbundles(%p: !llvm.ptr) {
+  %true = llvm.mlir.constant(true) : i1
   %0 = llvm.mlir.constant(8 : i32) : i32
-  // CHECK: call void @llvm.assume(i1 %{{.+}}) [ "align"(ptr %{{.+}}, i32 8) ]
-  llvm.intr.assume %cond ["align"(%p, %0 : !llvm.ptr, i32)] : i1
+  // CHECK: call void @llvm.assume(i1 true) [ "align"(ptr %{{.+}}, i32 8) ]
+  llvm.intr.assume %true ["align"(%p, %0 : !llvm.ptr, i32)] : i1
   llvm.return
 }