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Lower signed-divisions without rounding to ashr instructions 

llvm-svn: 238929
This commit is contained in:
Tobias Grosser 2015-06-03 15:14:58 +00:00
parent 14c4dab603
commit 244c8297cf
2 changed files with 10 additions and 5 deletions
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7
polly/lib/CodeGen/IslExprBuilder.cpp
View File

@ -295,6 +295,13 @@ Value *IslExprBuilder::createOpBin(__isl_take isl_ast_expr *Expr) {
Res = Builder.CreateNSWMul(LHS, RHS);
break;
case isl_ast_op_div:
if (auto *Const = dyn_cast<ConstantInt>(RHS)) {
auto &Val = Const->getValue();
if (Val.isPowerOf2() && Val.isNonNegative()) {
Res = Builder.CreateAShr(LHS, Val.ceilLogBase2(), "pexp.div.shr");
break;
}
}
Res = Builder.CreateSDiv(LHS, RHS, "pexp.div");
break;
case isl_ast_op_pdiv_q: // Dividend is non-negative

8
polly/test/Isl/CodeGen/exprModDiv.ll
View File

@ -46,10 +46,8 @@
; POW2: %polly.access.A6 = getelementptr float, float* %A, i64 %pexp.pdiv_r
; A[i / 128]
; POW2: %pexp.div = sdiv i64 %polly.indvar, 128
; POW2: %pexp.div.shr = ashr i64 %polly.indvar, 7
; POW2: %polly.access.B8 = getelementptr float, float* %B, i64 %pexp.div
;
; FIXME: Make isl mark this as an udiv expression.
; #define floord(n,d) ((n < 0) ? (n - d + 1) : n) / d
; A[p + 128 * floord(-p - 1, 128) + 128]
@ -62,8 +60,8 @@
; POW2: %polly.access.A10 = getelementptr float, float* %A, i64 %24
; A[p / 128]
; POW2: %pexp.div12 = sdiv i64 %p, 128
; POW2: %polly.access.B13 = getelementptr float, float* %B, i64 %pexp.div12
; POW2: %pexp.div.shr12 = ashr i64 %p, 7
; POW2: %polly.access.B13 = getelementptr float, float* %B, i64 %pexp.div.shr12
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"