From 0bbcb191e387ee471b16046eb29a4bc9f2666dcf Mon Sep 17 00:00:00 2001
From: Johannes Doerfert <johannes@jdoerfert.de>
Date: Thu, 12 Aug 2021 09:52:24 -0500
Subject: [PATCH] [Attributor][FIX] Guard constant casts with type size checks

(cherry picked from commit 5f543919b2646d36f2ddc1424acdd555bfcebe4f)
---
 lib/Transforms/IPO/Attributor.cpp             | 10 ++--
 .../Attributor/value-simplify-pointer-info.ll | 60 +++++++++++++++++++
 2 files changed, 66 insertions(+), 4 deletions(-)

diff --git a/lib/Transforms/IPO/Attributor.cpp b/lib/Transforms/IPO/Attributor.cpp
index 5fecbf35fef..91b16ec66ee 100644
--- a/lib/Transforms/IPO/Attributor.cpp
+++ b/lib/Transforms/IPO/Attributor.cpp
@@ -251,10 +251,12 @@ Value *AA::getWithType(Value &V, Type &Ty) {
       return Constant::getNullValue(&Ty);
     if (C->getType()->isPointerTy() && Ty.isPointerTy())
       return ConstantExpr::getPointerCast(C, &Ty);
-    if (C->getType()->isIntegerTy() && Ty.isIntegerTy())
-      return ConstantExpr::getTrunc(C, &Ty, /* OnlyIfReduced */ true);
-    if (C->getType()->isFloatingPointTy() && Ty.isFloatingPointTy())
-      return ConstantExpr::getFPTrunc(C, &Ty, /* OnlyIfReduced */ true);
+    if (C->getType()->getPrimitiveSizeInBits() >= Ty.getPrimitiveSizeInBits()) {
+      if (C->getType()->isIntegerTy() && Ty.isIntegerTy())
+        return ConstantExpr::getTrunc(C, &Ty, /* OnlyIfReduced */ true);
+      if (C->getType()->isFloatingPointTy() && Ty.isFloatingPointTy())
+        return ConstantExpr::getFPTrunc(C, &Ty, /* OnlyIfReduced */ true);
+    }
   }
   return nullptr;
 }
diff --git a/test/Transforms/Attributor/value-simplify-pointer-info.ll b/test/Transforms/Attributor/value-simplify-pointer-info.ll
index fdb974f003a..80b636951aa 100644
--- a/test/Transforms/Attributor/value-simplify-pointer-info.ll
+++ b/test/Transforms/Attributor/value-simplify-pointer-info.ll
@@ -26,6 +26,8 @@
 @a1 = internal global i32 zeroinitializer
 @a2 = internal global i32 zeroinitializer
 @a3 = internal global i32 undef
+@bytes1 = internal global i32 undef
+@bytes2 = internal global i32 undef
 
 ;.
 ; CHECK: @[[GLOBALBYTES:[a-zA-Z0-9_$"\\.-]+]] = global [1024 x i8] zeroinitializer, align 16
@@ -48,6 +50,8 @@
 ; CHECK: @[[A1:[a-zA-Z0-9_$"\\.-]+]] = internal global i32 0
 ; CHECK: @[[A2:[a-zA-Z0-9_$"\\.-]+]] = internal global i32 0
 ; CHECK: @[[A3:[a-zA-Z0-9_$"\\.-]+]] = internal global i32 undef
+; CHECK: @[[BYTES1:[a-zA-Z0-9_$"\\.-]+]] = internal global i32 undef
+; CHECK: @[[BYTES2:[a-zA-Z0-9_$"\\.-]+]] = internal global i32 undef
 ;.
 define void @write_arg(i32* %p, i32 %v) {
 ; IS__TUNIT____: Function Attrs: argmemonly nofree nosync nounwind willreturn writeonly
@@ -3230,6 +3234,62 @@ end:
   ret i8 %add
 }
 
+define i8 @cast_and_load_1() {
+; IS__TUNIT_OPM: Function Attrs: nofree nosync nounwind willreturn
+; IS__TUNIT_OPM-LABEL: define {{[^@]+}}@cast_and_load_1
+; IS__TUNIT_OPM-SAME: () #[[ATTR4]] {
+; IS__TUNIT_OPM-NEXT:    store i32 42, i32* @bytes1, align 4
+; IS__TUNIT_OPM-NEXT:    [[L:%.*]] = load i8, i8* bitcast (i32* @bytes1 to i8*), align 4
+; IS__TUNIT_OPM-NEXT:    ret i8 [[L]]
+;
+; IS__TUNIT_NPM: Function Attrs: nofree nosync nounwind willreturn
+; IS__TUNIT_NPM-LABEL: define {{[^@]+}}@cast_and_load_1
+; IS__TUNIT_NPM-SAME: () #[[ATTR2]] {
+; IS__TUNIT_NPM-NEXT:    store i32 42, i32* @bytes1, align 4
+; IS__TUNIT_NPM-NEXT:    [[L:%.*]] = load i8, i8* bitcast (i32* @bytes1 to i8*), align 4
+; IS__TUNIT_NPM-NEXT:    ret i8 [[L]]
+;
+; IS__CGSCC____: Function Attrs: nofree norecurse nosync nounwind willreturn
+; IS__CGSCC____-LABEL: define {{[^@]+}}@cast_and_load_1
+; IS__CGSCC____-SAME: () #[[ATTR5]] {
+; IS__CGSCC____-NEXT:    store i32 42, i32* @bytes1, align 4
+; IS__CGSCC____-NEXT:    [[L:%.*]] = load i8, i8* bitcast (i32* @bytes1 to i8*), align 4
+; IS__CGSCC____-NEXT:    ret i8 [[L]]
+;
+  store i32 42, i32* @bytes1
+  %bc = bitcast i32* @bytes1 to i8*
+  %l = load i8, i8* %bc
+  ret i8 %l
+}
+
+define i64 @cast_and_load_2() {
+; IS__TUNIT_OPM: Function Attrs: nofree nosync nounwind willreturn
+; IS__TUNIT_OPM-LABEL: define {{[^@]+}}@cast_and_load_2
+; IS__TUNIT_OPM-SAME: () #[[ATTR4]] {
+; IS__TUNIT_OPM-NEXT:    store i32 42, i32* @bytes2, align 4
+; IS__TUNIT_OPM-NEXT:    [[L:%.*]] = load i64, i64* bitcast (i32* @bytes2 to i64*), align 4
+; IS__TUNIT_OPM-NEXT:    ret i64 [[L]]
+;
+; IS__TUNIT_NPM: Function Attrs: nofree nosync nounwind willreturn
+; IS__TUNIT_NPM-LABEL: define {{[^@]+}}@cast_and_load_2
+; IS__TUNIT_NPM-SAME: () #[[ATTR2]] {
+; IS__TUNIT_NPM-NEXT:    store i32 42, i32* @bytes2, align 4
+; IS__TUNIT_NPM-NEXT:    [[L:%.*]] = load i64, i64* bitcast (i32* @bytes2 to i64*), align 4
+; IS__TUNIT_NPM-NEXT:    ret i64 [[L]]
+;
+; IS__CGSCC____: Function Attrs: nofree norecurse nosync nounwind willreturn
+; IS__CGSCC____-LABEL: define {{[^@]+}}@cast_and_load_2
+; IS__CGSCC____-SAME: () #[[ATTR5]] {
+; IS__CGSCC____-NEXT:    store i32 42, i32* @bytes2, align 4
+; IS__CGSCC____-NEXT:    [[L:%.*]] = load i64, i64* bitcast (i32* @bytes2 to i64*), align 4
+; IS__CGSCC____-NEXT:    ret i64 [[L]]
+;
+  store i32 42, i32* @bytes2
+  %bc = bitcast i32* @bytes2 to i64*
+  %l = load i64, i64* %bc
+  ret i64 %l
+}
+
 !llvm.module.flags = !{!0, !1}
 !llvm.ident = !{!2}