diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp --- a/llvm/lib/Analysis/ValueTracking.cpp +++ b/llvm/lib/Analysis/ValueTracking.cpp @@ -4766,6 +4766,12 @@ // TODO: Some instructions are guaranteed to return neither undef // nor poison if their arguments are not poison/undef. + if (auto *A = dyn_cast(V)) { + // NoUndef does not guarantee that paddings are not undef. + if (A->hasAttribute(Attribute::NoUndef)) + return true; + } + if (auto *C = dyn_cast(V)) { // TODO: We can analyze ConstExpr by opcode to determine if there is any // possibility of poison. diff --git a/llvm/test/Transforms/InstSimplify/freeze-noundef.ll b/llvm/test/Transforms/InstSimplify/freeze-noundef.ll --- a/llvm/test/Transforms/InstSimplify/freeze-noundef.ll +++ b/llvm/test/Transforms/InstSimplify/freeze-noundef.ll @@ -3,8 +3,7 @@ define i8 @noundef(i8 noundef %x) { ; CHECK-LABEL: @noundef( -; CHECK-NEXT: [[Y:%.*]] = freeze i8 [[X:%.*]] -; CHECK-NEXT: ret i8 [[Y]] +; CHECK-NEXT: ret i8 [[X:%.*]] ; %y = freeze i8 %x ret i8 %y @@ -13,14 +12,14 @@ define i1 @icmp(i8 noundef %x, i8 noundef %y) { ; CHECK-LABEL: @icmp( ; CHECK-NEXT: [[C:%.*]] = icmp eq i8 [[X:%.*]], [[Y:%.*]] -; CHECK-NEXT: [[F:%.*]] = freeze i1 [[C]] -; CHECK-NEXT: ret i1 [[F]] +; CHECK-NEXT: ret i1 [[C]] ; %c = icmp eq i8 %x, %y %f = freeze i1 %c ret i1 %f } +; TODO: should look into binary operations define i1 @or(i1 noundef %x, i1 noundef %x2) { ; CHECK-LABEL: @or( ; CHECK-NEXT: [[Y:%.*]] = or i1 [[X:%.*]], [[X2:%.*]] @@ -43,6 +42,7 @@ ret i1 %z } +; TODO: should look into binary operations define i8 @add(i8 noundef %x) { ; CHECK-LABEL: @add( ; CHECK-NEXT: [[Y:%.*]] = add i8 [[X:%.*]], 1 @@ -67,13 +67,13 @@ define {i8, i32} @aggr({i8, i32} noundef %x) { ; CHECK-LABEL: @aggr( -; CHECK-NEXT: [[Y:%.*]] = freeze { i8, i32 } [[X:%.*]] -; CHECK-NEXT: ret { i8, i32 } [[Y]] +; CHECK-NEXT: ret { i8, i32 } [[X:%.*]] ; %y = freeze {i8, i32} %x ret {i8, i32} %y } +; TODO: should look into extract operations define i32 @extract({i8, i32} noundef %x) { ; CHECK-LABEL: @extract( ; CHECK-NEXT: [[Y:%.*]] = extractvalue { i8, i32 } [[X:%.*]], 1 @@ -85,6 +85,7 @@ ret i32 %z } +; TODO: should look into extract operations define i32 @extract2({i8, {i8, i32}} noundef %x) { ; CHECK-LABEL: @extract2( ; CHECK-NEXT: [[Y:%.*]] = extractvalue { i8, { i8, i32 } } [[X:%.*]], 1