Removeing dead code

Couldn't produce a test to hit removed code. The maximum (power of 2) value you can store in any iXX variable is 2^XX-1. The 2^XX can't fit into iXX
intel · Sep 19, 2024 · 5089830 · 5089830
1 parent 5c788e5
commit 5089830
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Showing 2 changed files with 13 additions and 5 deletions.
diff --git a/IGC/Compiler/Optimizer/IntDivConstantReduction.cpp b/IGC/Compiler/Optimizer/IntDivConstantReduction.cpp
@@ -170,11 +170,8 @@ struct IntDivConstantReduction : public FunctionPass
         int shiftAmt = divisor.logBase2();
         Value *result;
         if (isMod) {
-            if (shiftAmt == bitSize) { // X % MAX_VAL = X
-                result = dividend;
-            } else { // X % 2^K = (X & ((1<<K)-1))
-                result = B.CreateAnd(dividend, ((1ull << shiftAmt)-1));
-            }
+            // X % 2^K = (X & ((1<<K)-1))
+            result = B.CreateAnd(dividend, ((1ull << shiftAmt)-1));
         } else {
             result = B.CreateLShr(dividend, shiftAmt);
         }

diff --git a/IGC/Compiler/tests/IntDivConstantReduction/basic.ll b/IGC/Compiler/tests/IntDivConstantReduction/basic.ll
@@ -135,6 +135,17 @@ define spir_kernel void @test_sdiv_max(i32 %src1) {
   ret void
 }
 
+define spir_kernel void @test_rem_pow_of_2(i32 %src1) {
+; CHECK-LABEL: @test_rem_pow_of_2(
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[SRC1:%.*]], 2147483647
+; CHECK-NEXT:    call void @use.i32(i32 [[TMP1]])
+; CHECK-NEXT:    ret void
+;
+  %1 = urem i32 %src1, 2147483648 ; <- 2^31
+  call void @use.i32(i32 %1)
+  ret void
+}
+
 define spir_kernel void @test_udiv_max(i32 %src1) {
 ; CHECK-LABEL: @test_udiv_max(
 ; CHECK:    [[Q_APPX:%.*]] = call i32 @llvm.genx.GenISA.umulH.i32(i32 %src1, i32 -2147483647)