[llvm] [InstCombine] Canonicalize `(uitofp x)` -> `(sitofp x)` if `x >= 0` (PR #82404)
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Tue Feb 20 11:03:29 PST 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-transforms
Author: None (goldsteinn)
<details>
<summary>Changes</summary>
- **[InstCombine] Add simple test for value of canonicalizing `uitofp` -> `sitofp`; NFC**
- **[InstCombine] Canonicalize `(uitofp x)` -> `(sitofp x)` if `x >= 0`**
---
Full diff: https://github.com/llvm/llvm-project/pull/82404.diff
5 Files Affected:
- (modified) llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp (+5-1)
- (modified) llvm/test/Transforms/InstCombine/add-sitofp.ll (+19)
- (modified) llvm/test/Transforms/InstCombine/clamp-to-minmax.ll (+2-2)
- (modified) llvm/test/Transforms/InstCombine/fpcast.ll (+6-6)
- (modified) llvm/test/Transforms/InstCombine/sitofp.ll (+1-1)
``````````diff
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
index ed47de287302ed..c22f1d8561ebbb 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -1929,7 +1929,11 @@ Instruction *InstCombinerImpl::visitFPToSI(FPToSIInst &FI) {
}
Instruction *InstCombinerImpl::visitUIToFP(CastInst &CI) {
- return commonCastTransforms(CI);
+ if (Instruction *R = commonCastTransforms(CI))
+ return R;
+ if (isKnownNonNegative(CI.getOperand(0), SQ))
+ return new SIToFPInst(CI.getOperand(0), CI.getType());
+ return nullptr;
}
Instruction *InstCombinerImpl::visitSIToFP(CastInst &CI) {
diff --git a/llvm/test/Transforms/InstCombine/add-sitofp.ll b/llvm/test/Transforms/InstCombine/add-sitofp.ll
index db44b806593b64..0b25f7acb085ba 100644
--- a/llvm/test/Transforms/InstCombine/add-sitofp.ll
+++ b/llvm/test/Transforms/InstCombine/add-sitofp.ll
@@ -63,6 +63,25 @@ define double @test_2(i32 %a, i32 %b) {
ret double %res
}
+define double @test_2_uitofp(i32 %a, i32 %b) {
+; CHECK-LABEL: @test_2_uitofp(
+; CHECK-NEXT: [[A_AND:%.*]] = and i32 [[A:%.*]], 1073741823
+; CHECK-NEXT: [[B_AND:%.*]] = and i32 [[B:%.*]], 1073741823
+; CHECK-NEXT: [[ADDCONV:%.*]] = add nuw nsw i32 [[A_AND]], [[B_AND]]
+; CHECK-NEXT: [[RES:%.*]] = sitofp i32 [[ADDCONV]] to double
+; CHECK-NEXT: ret double [[RES]]
+;
+ ; Drop two highest bits to guarantee that %a + %b doesn't overflow
+ %a_and = and i32 %a, 1073741823
+ %b_and = and i32 %b, 1073741823
+
+ %a_and_fp = uitofp i32 %a_and to double
+ %b_and_fp = uitofp i32 %b_and to double
+
+ %res = fadd double %a_and_fp, %b_and_fp
+ ret double %res
+}
+
define float @test_2_neg(i32 %a, i32 %b) {
; CHECK-LABEL: @test_2_neg(
; CHECK-NEXT: [[A_AND:%.*]] = and i32 [[A:%.*]], 1073741823
diff --git a/llvm/test/Transforms/InstCombine/clamp-to-minmax.ll b/llvm/test/Transforms/InstCombine/clamp-to-minmax.ll
index fad1176cc18fac..d997ab2e24bc5b 100644
--- a/llvm/test/Transforms/InstCombine/clamp-to-minmax.ll
+++ b/llvm/test/Transforms/InstCombine/clamp-to-minmax.ll
@@ -472,7 +472,7 @@ define float @ui32_clamp_and_cast_to_float(i32 %x) {
; CHECK-LABEL: @ui32_clamp_and_cast_to_float(
; CHECK-NEXT: [[LO_CMP:%.*]] = icmp eq i32 [[X:%.*]], 0
; CHECK-NEXT: [[MIN1:%.*]] = call i32 @llvm.umin.i32(i32 [[X]], i32 255)
-; CHECK-NEXT: [[MIN:%.*]] = uitofp i32 [[MIN1]] to float
+; CHECK-NEXT: [[MIN:%.*]] = sitofp i32 [[MIN1]] to float
; CHECK-NEXT: [[R:%.*]] = select i1 [[LO_CMP]], float 1.000000e+00, float [[MIN]]
; CHECK-NEXT: ret float [[R]]
;
@@ -488,7 +488,7 @@ define float @ui64_clamp_and_cast_to_float(i64 %x) {
; CHECK-LABEL: @ui64_clamp_and_cast_to_float(
; CHECK-NEXT: [[LO_CMP:%.*]] = icmp eq i64 [[X:%.*]], 0
; CHECK-NEXT: [[MIN1:%.*]] = call i64 @llvm.umin.i64(i64 [[X]], i64 255)
-; CHECK-NEXT: [[MIN:%.*]] = uitofp i64 [[MIN1]] to float
+; CHECK-NEXT: [[MIN:%.*]] = sitofp i64 [[MIN1]] to float
; CHECK-NEXT: [[R:%.*]] = select i1 [[LO_CMP]], float 1.000000e+00, float [[MIN]]
; CHECK-NEXT: ret float [[R]]
;
diff --git a/llvm/test/Transforms/InstCombine/fpcast.ll b/llvm/test/Transforms/InstCombine/fpcast.ll
index 3e5c6fd20b12da..ca47f068b4860f 100644
--- a/llvm/test/Transforms/InstCombine/fpcast.ll
+++ b/llvm/test/Transforms/InstCombine/fpcast.ll
@@ -266,7 +266,7 @@ define half @uint_to_fptrunc(i32 %x) {
define half @masked_uint_to_fptrunc1(i32 %x) {
; CHECK-LABEL: @masked_uint_to_fptrunc1(
; CHECK-NEXT: [[M:%.*]] = and i32 [[X:%.*]], 16777215
-; CHECK-NEXT: [[R:%.*]] = uitofp i32 [[M]] to half
+; CHECK-NEXT: [[R:%.*]] = sitofp i32 [[M]] to half
; CHECK-NEXT: ret half [[R]]
;
%m = and i32 %x, 16777215
@@ -278,7 +278,7 @@ define half @masked_uint_to_fptrunc1(i32 %x) {
define half @masked_uint_to_fptrunc2(i32 %x) {
; CHECK-LABEL: @masked_uint_to_fptrunc2(
; CHECK-NEXT: [[M:%.*]] = lshr i32 [[X:%.*]], 8
-; CHECK-NEXT: [[R:%.*]] = uitofp i32 [[M]] to half
+; CHECK-NEXT: [[R:%.*]] = sitofp i32 [[M]] to half
; CHECK-NEXT: ret half [[R]]
;
%m = lshr i32 %x, 8
@@ -290,7 +290,7 @@ define half @masked_uint_to_fptrunc2(i32 %x) {
define half @masked_uint_to_fptrunc3(i32 %x) {
; CHECK-LABEL: @masked_uint_to_fptrunc3(
; CHECK-NEXT: [[M:%.*]] = lshr i32 [[X:%.*]], 7
-; CHECK-NEXT: [[F:%.*]] = uitofp i32 [[M]] to float
+; CHECK-NEXT: [[F:%.*]] = sitofp i32 [[M]] to float
; CHECK-NEXT: [[R:%.*]] = fptrunc float [[F]] to half
; CHECK-NEXT: ret half [[R]]
;
@@ -314,7 +314,7 @@ define double @uint_to_fpext(i32 %x) {
define double @masked_uint_to_fpext1(i32 %x) {
; CHECK-LABEL: @masked_uint_to_fpext1(
; CHECK-NEXT: [[M:%.*]] = and i32 [[X:%.*]], 16777215
-; CHECK-NEXT: [[R:%.*]] = uitofp i32 [[M]] to double
+; CHECK-NEXT: [[R:%.*]] = sitofp i32 [[M]] to double
; CHECK-NEXT: ret double [[R]]
;
%m = and i32 %x, 16777215
@@ -326,7 +326,7 @@ define double @masked_uint_to_fpext1(i32 %x) {
define double @masked_uint_to_fpext2(i32 %x) {
; CHECK-LABEL: @masked_uint_to_fpext2(
; CHECK-NEXT: [[M:%.*]] = lshr i32 [[X:%.*]], 8
-; CHECK-NEXT: [[R:%.*]] = uitofp i32 [[M]] to double
+; CHECK-NEXT: [[R:%.*]] = sitofp i32 [[M]] to double
; CHECK-NEXT: ret double [[R]]
;
%m = lshr i32 %x, 8
@@ -338,7 +338,7 @@ define double @masked_uint_to_fpext2(i32 %x) {
define double @masked_uint_to_fpext3(i32 %x) {
; CHECK-LABEL: @masked_uint_to_fpext3(
; CHECK-NEXT: [[M:%.*]] = lshr i32 [[X:%.*]], 7
-; CHECK-NEXT: [[F:%.*]] = uitofp i32 [[M]] to float
+; CHECK-NEXT: [[F:%.*]] = sitofp i32 [[M]] to float
; CHECK-NEXT: [[R:%.*]] = fpext float [[F]] to double
; CHECK-NEXT: ret double [[R]]
;
diff --git a/llvm/test/Transforms/InstCombine/sitofp.ll b/llvm/test/Transforms/InstCombine/sitofp.ll
index 5e0cf944880071..086323624a2073 100644
--- a/llvm/test/Transforms/InstCombine/sitofp.ll
+++ b/llvm/test/Transforms/InstCombine/sitofp.ll
@@ -256,7 +256,7 @@ define i25 @consider_lowbits_masked_input(i25 %A) {
define i32 @overflow_masked_input(i32 %A) {
; CHECK-LABEL: @overflow_masked_input(
; CHECK-NEXT: [[M:%.*]] = and i32 [[A:%.*]], 16777217
-; CHECK-NEXT: [[B:%.*]] = uitofp i32 [[M]] to float
+; CHECK-NEXT: [[B:%.*]] = sitofp i32 [[M]] to float
; CHECK-NEXT: [[C:%.*]] = fptoui float [[B]] to i32
; CHECK-NEXT: ret i32 [[C]]
;
``````````
</details>
https://github.com/llvm/llvm-project/pull/82404
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