leonardchan updated this revision to Diff 184888.
leonardchan retitled this revision from "[Fixed Point Arithmetic] Check against
source value when converting during saturation" to "[Fixed Point Arithmetic]
Avoid resizing for types with the same width".
leonardchan edited the summary of this revision.
Repository:
rC Clang
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D57553/new/
https://reviews.llvm.org/D57553
Files:
clang/lib/CodeGen/CGExprScalar.cpp
clang/test/Frontend/fixed_point_conversions.c
Index: clang/test/Frontend/fixed_point_conversions.c
===================================================================
--- clang/test/Frontend/fixed_point_conversions.c
+++ clang/test/Frontend/fixed_point_conversions.c
@@ -186,14 +186,12 @@
// Accum to Fract, increasing scale
sat_lf = sat_a;
// DEFAULT: [[OLD_ACCUM:%[0-9a-z]+]] = load i32, i32* %sat_a, align 4
- // DEFAULT-NEXT: [[ACCUM:%[0-9a-z]+]] = sext i32 [[OLD_ACCUM]] to i48
- // DEFAULT-NEXT: [[FRACT:%[0-9a-z]+]] = shl i48 [[ACCUM]], 16
- // DEFAULT-NEXT: [[USE_MAX:%[0-9a-z]+]] = icmp sgt i48 [[FRACT]], 2147483647
- // DEFAULT-NEXT: [[RESULT:%[0-9a-z]+]] = select i1 [[USE_MAX]], i48
2147483647, i48 [[FRACT]]
- // DEFAULT-NEXT: [[USE_MIN:%[0-9a-z]+]] = icmp slt i48 [[RESULT]],
-2147483648
- // DEFAULT-NEXT: [[RESULT2:%[0-9a-z]+]] = select i1 [[USE_MIN]], i48
-2147483648, i48 [[RESULT]]
- // DEFAULT-NEXT: [[RESULT_TRUNC:%[0-9a-z]+]] = trunc i48 [[RESULT2]] to i32
- // DEFAULT-NEXT: store i32 [[RESULT_TRUNC]], i32* %sat_lf, align 4
+ // DEFAULT-NEXT: [[FRACT:%[0-9a-z]+]] = shl i32 [[OLD_ACCUM]], 16
+ // DEFAULT-NEXT: [[USE_MAX:%[0-9a-z]+]] = icmp sgt i32 [[FRACT]], 2147483647
+ // DEFAULT-NEXT: [[RESULT:%[0-9a-z]+]] = select i1 [[USE_MAX]], i32
2147483647, i32 [[FRACT]]
+ // DEFAULT-NEXT: [[USE_MIN:%[0-9a-z]+]] = icmp slt i32 [[RESULT]],
-2147483648
+ // DEFAULT-NEXT: [[RESULT2:%[0-9a-z]+]] = select i1 [[USE_MIN]], i32
-2147483648, i32 [[RESULT]]
+ // DEFAULT-NEXT: store i32 [[RESULT2]], i32* %sat_lf, align 4
// Signed to unsigned, decreasing scale
_Sat _Accum sat_a2;
@@ -218,12 +216,10 @@
// Signed to unsigned, increasing scale
sat_ua = sat_a;
// DEFAULT: [[OLD_ACCUM:%[0-9a-z]+]] = load i32, i32* %sat_a, align 4
- // DEFAULT-NEXT: [[ACCUM_EXT:%[0-9a-z]+]] = sext i32 [[OLD_ACCUM]] to i33
- // DEFAULT-NEXT: [[ACCUM:%[0-9a-z]+]] = shl i33 [[ACCUM_EXT]], 1
- // DEFAULT-NEXT: [[USE_MIN:%[0-9a-z]+]] = icmp slt i33 [[ACCUM]], 0
- // DEFAULT-NEXT: [[RESULT2:%[0-9a-z]+]] = select i1 [[USE_MIN]], i33 0, i33
[[ACCUM]]
- // DEFAULT-NEXT: [[RESULT_TRUNC:%[0-9a-z]+]] = trunc i33 [[RESULT2]] to i32
- // DEFAULT-NEXT: store i32 [[RESULT_TRUNC]], i32* %sat_ua, align 4
+ // DEFAULT-NEXT: [[ACCUM:%[0-9a-z]+]] = shl i32 [[OLD_ACCUM]], 1
+ // DEFAULT-NEXT: [[USE_MIN:%[0-9a-z]+]] = icmp slt i32 [[ACCUM]], 0
+ // DEFAULT-NEXT: [[RESULT2:%[0-9a-z]+]] = select i1 [[USE_MIN]], i32 0, i32
[[ACCUM]]
+ // DEFAULT-NEXT: store i32 [[RESULT2]], i32* %sat_ua, align 4
// SAME: [[ACCUM:%[0-9a-z]+]] = load i32, i32* %sat_a, align 4
// SAME-NEXT: [[USE_MIN:%[0-9a-z]+]] = icmp slt i32 [[ACCUM]], 0
// SAME-NEXT: [[RESULT:%[0-9a-z]+]] = select i1 [[USE_MIN]], i32 0, i32
[[ACCUM]]
Index: clang/lib/CodeGen/CGExprScalar.cpp
===================================================================
--- clang/lib/CodeGen/CGExprScalar.cpp
+++ clang/lib/CodeGen/CGExprScalar.cpp
@@ -1481,9 +1481,14 @@
// Adjust the number of fractional bits.
if (DstScale > SrcScale) {
// Compare to DstWidth to prevent resizing twice.
- ResultWidth = std::max(SrcWidth + DstScale - SrcScale, DstWidth);
- llvm::Type *UpscaledTy = Builder.getIntNTy(ResultWidth);
- Result = Builder.CreateIntCast(Result, UpscaledTy, SrcIsSigned,
"resize");
+ if (ResultWidth != DstWidth) {
+ // No rescaling is needed if both sides have the same resulting width.
+ // This would end up with a needless int cast.
+ ResultWidth = std::max(SrcWidth + DstScale - SrcScale, DstWidth);
+ llvm::Type *UpscaledTy = Builder.getIntNTy(ResultWidth);
+ Result =
+ Builder.CreateIntCast(Result, UpscaledTy, SrcIsSigned, "resize");
+ }
Result = Builder.CreateShl(Result, DstScale - SrcScale, "upscale");
} else if (DstScale < SrcScale) {
Result = SrcIsSigned ?
Index: clang/test/Frontend/fixed_point_conversions.c
===================================================================
--- clang/test/Frontend/fixed_point_conversions.c
+++ clang/test/Frontend/fixed_point_conversions.c
@@ -186,14 +186,12 @@
// Accum to Fract, increasing scale
sat_lf = sat_a;
// DEFAULT: [[OLD_ACCUM:%[0-9a-z]+]] = load i32, i32* %sat_a, align 4
- // DEFAULT-NEXT: [[ACCUM:%[0-9a-z]+]] = sext i32 [[OLD_ACCUM]] to i48
- // DEFAULT-NEXT: [[FRACT:%[0-9a-z]+]] = shl i48 [[ACCUM]], 16
- // DEFAULT-NEXT: [[USE_MAX:%[0-9a-z]+]] = icmp sgt i48 [[FRACT]], 2147483647
- // DEFAULT-NEXT: [[RESULT:%[0-9a-z]+]] = select i1 [[USE_MAX]], i48 2147483647, i48 [[FRACT]]
- // DEFAULT-NEXT: [[USE_MIN:%[0-9a-z]+]] = icmp slt i48 [[RESULT]], -2147483648
- // DEFAULT-NEXT: [[RESULT2:%[0-9a-z]+]] = select i1 [[USE_MIN]], i48 -2147483648, i48 [[RESULT]]
- // DEFAULT-NEXT: [[RESULT_TRUNC:%[0-9a-z]+]] = trunc i48 [[RESULT2]] to i32
- // DEFAULT-NEXT: store i32 [[RESULT_TRUNC]], i32* %sat_lf, align 4
+ // DEFAULT-NEXT: [[FRACT:%[0-9a-z]+]] = shl i32 [[OLD_ACCUM]], 16
+ // DEFAULT-NEXT: [[USE_MAX:%[0-9a-z]+]] = icmp sgt i32 [[FRACT]], 2147483647
+ // DEFAULT-NEXT: [[RESULT:%[0-9a-z]+]] = select i1 [[USE_MAX]], i32 2147483647, i32 [[FRACT]]
+ // DEFAULT-NEXT: [[USE_MIN:%[0-9a-z]+]] = icmp slt i32 [[RESULT]], -2147483648
+ // DEFAULT-NEXT: [[RESULT2:%[0-9a-z]+]] = select i1 [[USE_MIN]], i32 -2147483648, i32 [[RESULT]]
+ // DEFAULT-NEXT: store i32 [[RESULT2]], i32* %sat_lf, align 4
// Signed to unsigned, decreasing scale
_Sat _Accum sat_a2;
@@ -218,12 +216,10 @@
// Signed to unsigned, increasing scale
sat_ua = sat_a;
// DEFAULT: [[OLD_ACCUM:%[0-9a-z]+]] = load i32, i32* %sat_a, align 4
- // DEFAULT-NEXT: [[ACCUM_EXT:%[0-9a-z]+]] = sext i32 [[OLD_ACCUM]] to i33
- // DEFAULT-NEXT: [[ACCUM:%[0-9a-z]+]] = shl i33 [[ACCUM_EXT]], 1
- // DEFAULT-NEXT: [[USE_MIN:%[0-9a-z]+]] = icmp slt i33 [[ACCUM]], 0
- // DEFAULT-NEXT: [[RESULT2:%[0-9a-z]+]] = select i1 [[USE_MIN]], i33 0, i33 [[ACCUM]]
- // DEFAULT-NEXT: [[RESULT_TRUNC:%[0-9a-z]+]] = trunc i33 [[RESULT2]] to i32
- // DEFAULT-NEXT: store i32 [[RESULT_TRUNC]], i32* %sat_ua, align 4
+ // DEFAULT-NEXT: [[ACCUM:%[0-9a-z]+]] = shl i32 [[OLD_ACCUM]], 1
+ // DEFAULT-NEXT: [[USE_MIN:%[0-9a-z]+]] = icmp slt i32 [[ACCUM]], 0
+ // DEFAULT-NEXT: [[RESULT2:%[0-9a-z]+]] = select i1 [[USE_MIN]], i32 0, i32 [[ACCUM]]
+ // DEFAULT-NEXT: store i32 [[RESULT2]], i32* %sat_ua, align 4
// SAME: [[ACCUM:%[0-9a-z]+]] = load i32, i32* %sat_a, align 4
// SAME-NEXT: [[USE_MIN:%[0-9a-z]+]] = icmp slt i32 [[ACCUM]], 0
// SAME-NEXT: [[RESULT:%[0-9a-z]+]] = select i1 [[USE_MIN]], i32 0, i32 [[ACCUM]]
Index: clang/lib/CodeGen/CGExprScalar.cpp
===================================================================
--- clang/lib/CodeGen/CGExprScalar.cpp
+++ clang/lib/CodeGen/CGExprScalar.cpp
@@ -1481,9 +1481,14 @@
// Adjust the number of fractional bits.
if (DstScale > SrcScale) {
// Compare to DstWidth to prevent resizing twice.
- ResultWidth = std::max(SrcWidth + DstScale - SrcScale, DstWidth);
- llvm::Type *UpscaledTy = Builder.getIntNTy(ResultWidth);
- Result = Builder.CreateIntCast(Result, UpscaledTy, SrcIsSigned, "resize");
+ if (ResultWidth != DstWidth) {
+ // No rescaling is needed if both sides have the same resulting width.
+ // This would end up with a needless int cast.
+ ResultWidth = std::max(SrcWidth + DstScale - SrcScale, DstWidth);
+ llvm::Type *UpscaledTy = Builder.getIntNTy(ResultWidth);
+ Result =
+ Builder.CreateIntCast(Result, UpscaledTy, SrcIsSigned, "resize");
+ }
Result = Builder.CreateShl(Result, DstScale - SrcScale, "upscale");
} else if (DstScale < SrcScale) {
Result = SrcIsSigned ?
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