Mark the multiply which occurs as part of performing pointer

arithmetic on a VLA as 'nsw', per discussion with djg, and
implement pointer arithmetic (other than array accesses) and
pointer subtraction for VLA types.

llvm-svn: 133855

2 files changed, 46 insertions, 3 deletions

diff --git a/clang/test/CodeGen/vla.c b/clang/test/CodeGen/vla.c
index f7cba25d934..c9612bc1603 100644
--- a/clang/test/CodeGen/vla.c
+++ b/clang/test/CodeGen/vla.c
@@ -94,7 +94,7 @@ double test_PR8567(int n, double (*p)[n][5]) {
   // CHECK-NEXT: store
   // CHECK-NEXT: [[N:%.*]] = load i32* [[NV]], align 4
   // CHECK-NEXT: [[P:%.*]] = load [5 x double]** [[PV]], align 4
-  // CHECK-NEXT: [[T0:%.*]] = mul i32 1, [[N]]
+  // CHECK-NEXT: [[T0:%.*]] = mul nsw i32 1, [[N]]
   // CHECK-NEXT: [[T1:%.*]] = getelementptr inbounds [5 x double]* [[P]], i32 [[T0]]
   // CHECK-NEXT: [[T2:%.*]] = getelementptr inbounds [5 x double]* [[T1]], i32 2
   // CHECK-NEXT: [[T3:%.*]] = getelementptr inbounds [5 x double]* [[T2]], i32 0, i32 3
@@ -102,3 +102,46 @@ double test_PR8567(int n, double (*p)[n][5]) {
   // CHECK-NEXT: ret double [[T4]]
  return p[1][2][3];
 }
+
+int test4(unsigned n, char (*p)[n][n+1][6]) {
+  // CHECK:    define i32 @test4(
+  // CHECK:      [[N:%.*]] = alloca i32, align 4
+  // CHECK-NEXT: [[P:%.*]] = alloca [6 x i8]*, align 4
+  // CHECK-NEXT: [[P2:%.*]] = alloca [6 x i8]*, align 4
+  // CHECK-NEXT: store i32
+  // CHECK-NEXT: store [6 x i8]*
+
+  // VLA captures.
+  // CHECK-NEXT: [[DIM0:%.*]] = load i32* [[N]], align 4
+  // CHECK-NEXT: [[T0:%.*]] = load i32* [[N]], align 4
+  // CHECK-NEXT: [[DIM1:%.*]] = add i32 [[T0]], 1
+
+  // __typeof.  FIXME: does this really need to be loaded?
+  // CHECK-NEXT: load [6 x i8]** [[P]]
+
+  // CHECK-NEXT: [[T0:%.*]] = load [6 x i8]** [[P]], align 4
+  // CHECK-NEXT: [[T1:%.*]] = load i32* [[N]], align 4
+  // CHECK-NEXT: [[T2:%.*]] = udiv i32 [[T1]], 2
+  // CHECK-NEXT: [[T3:%.*]] = mul nuw i32 [[DIM0]], [[DIM1]]
+  // CHECK-NEXT: [[T4:%.*]] = mul nsw i32 [[T2]], [[T3]]
+  // CHECK-NEXT: [[T5:%.*]] = getelementptr inbounds [6 x i8]* [[T0]], i32 [[T4]]
+  // CHECK-NEXT: [[T6:%.*]] = load i32* [[N]], align 4
+  // CHECK-NEXT: [[T7:%.*]] = udiv i32 [[T6]], 4
+  // CHECK-NEXT: [[T8:%.*]] = sub i32 0, [[T7]]
+  // CHECK-NEXT: [[T9:%.*]] = mul nuw i32 [[DIM0]], [[DIM1]]
+  // CHECK-NEXT: [[T10:%.*]] = mul nsw i32 [[T8]], [[T9]]
+  // CHECK-NEXT: [[T11:%.*]] = getelementptr inbounds [6 x i8]* [[T5]], i32 [[T10]]
+  // CHECK-NEXT: store [6 x i8]* [[T11]], [6 x i8]** [[P2]], align 4
+  __typeof(p) p2 = (p + n/2) - n/4;
+
+  // CHECK-NEXT: [[T0:%.*]] = load [6 x i8]** [[P2]], align 4
+  // CHECK-NEXT: [[T1:%.*]] = load [6 x i8]** [[P]], align 4
+  // CHECK-NEXT: [[T2:%.*]] = ptrtoint [6 x i8]* [[T0]] to i32
+  // CHECK-NEXT: [[T3:%.*]] = ptrtoint [6 x i8]* [[T1]] to i32
+  // CHECK-NEXT: [[T4:%.*]] = sub i32 [[T2]], [[T3]]
+  // CHECK-NEXT: [[T5:%.*]] = mul nuw i32 [[DIM0]], [[DIM1]]
+  // CHECK-NEXT: [[T6:%.*]] = mul nuw i32 6, [[T5]]
+  // CHECK-NEXT: [[T7:%.*]] = sdiv exact i32 [[T4]], [[T6]]
+  // CHECK-NEXT: ret i32 [[T7]]
+  return p2 - p;
+}
diff --git a/clang/test/CodeGenCXX/vla.cpp b/clang/test/CodeGenCXX/vla.cpp
index cee00f27713..58cdf795ee5 100644
--- a/clang/test/CodeGenCXX/vla.cpp
+++ b/clang/test/CodeGenCXX/vla.cpp
@@ -24,14 +24,14 @@ void test0(void *array, int n) {
   array_t &ref = *(array_t*) array;
 
   // CHECK-NEXT: [[T0:%.*]] = load i16** [[REF]]
-  // CHECK-NEXT: [[T1:%.*]] = mul i64 1, [[DIM1]]
+  // CHECK-NEXT: [[T1:%.*]] = mul nsw i64 1, [[DIM1]]
   // CHECK-NEXT: [[T2:%.*]] = getelementptr inbounds i16* [[T0]], i64 [[T1]]
   // CHECK-NEXT: [[T3:%.*]] = getelementptr inbounds i16* [[T2]], i64 2
   // CHECK-NEXT: store i16 3, i16* [[T3]]
   ref[1][2] = 3;
 
   // CHECK-NEXT: [[T0:%.*]] = load i16** [[REF]]
-  // CHECK-NEXT: [[T1:%.*]] = mul i64 4, [[DIM1]]
+  // CHECK-NEXT: [[T1:%.*]] = mul nsw i64 4, [[DIM1]]
   // CHECK-NEXT: [[T2:%.*]] = getelementptr inbounds i16* [[T0]], i64 [[T1]]
   // CHECK-NEXT: [[T3:%.*]] = getelementptr inbounds i16* [[T2]], i64 5
   // CHECK-NEXT: [[T4:%.*]] = load i16* [[T3]]