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llvm-project/clang/test/Misc/loop-opt-setup.c

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Fix full unrolling with new pass manager. Last we looked at this and couldn't come up with a reason to change it, but with a pragma for full loop unrolling we bypass every other loop unroll and then fail to fully unroll a loop when the pragma is set. Move the OnlyWhenForced out of the check and into the initialization of the full unroll pass in the new pass manager. This doesn't show up with the old pass manager. Add a new option to opt so that we can turn off loop unrolling manually since this is a difference between clang and opt. Tested with check-clang and check-llvm.
2020-05-05 04:48:56 +08:00
// RUN: %clang -O1 -fexperimental-new-pass-manager -fno-unroll-loops -S -o - %s -emit-llvm | FileCheck %s -check-prefix=CHECK-NEWPM
// RUN: %clang -O1 -fno-experimental-new-pass-manager -fno-unroll-loops -S -o - %s -emit-llvm | FileCheck %s -check-prefix=CHECK-OLDPM
In the new pass manager use PTO.LoopUnrolling to determine when and how we will unroll loops. Also comment a few occasions where we need to know whether or not we're forcing the unwinder or not. The default before and after this patch is for LoopUnroll to be enabled, and for it to use a cost model to determine whether to unroll the loop (`OnlyWhenForced = false`). Before this patch, disabling loop unroll would not run the LoopUnroll pass. After this patch, the LoopUnroll pass is being run, but it restricts unrolling to only the loops marked by a pragma (`OnlyWhenForced = true`). In addition, this patch disables the UnrollAndJam pass when disabling unrolling. Testcase is in clang because it's controlling how the loop optimizer is being set up and there's no other way to trigger the behavior. llvm-svn: 374838
2019-10-15 06:56:07 +08:00
extern int a[16];
int b = 0;
int foo(void) {
#pragma unroll
for (int i = 0; i < 16; ++i)
a[i] = b += 2;
return b;
}
Fix full unrolling with new pass manager. Last we looked at this and couldn't come up with a reason to change it, but with a pragma for full loop unrolling we bypass every other loop unroll and then fail to fully unroll a loop when the pragma is set. Move the OnlyWhenForced out of the check and into the initialization of the full unroll pass in the new pass manager. This doesn't show up with the old pass manager. Add a new option to opt so that we can turn off loop unrolling manually since this is a difference between clang and opt. Tested with check-clang and check-llvm.
2020-05-05 04:48:56 +08:00
// Check br i1 to make sure that the loop is fully unrolled
// CHECK-LABEL-NEWPM: foo
// CHECK-NOT-NEWPM: br i1
// CHECK-LABEL-OLDPM: foo
// CHECK-NOT-OLDPM: br i1
In the new pass manager use PTO.LoopUnrolling to determine when and how we will unroll loops. Also comment a few occasions where we need to know whether or not we're forcing the unwinder or not. The default before and after this patch is for LoopUnroll to be enabled, and for it to use a cost model to determine whether to unroll the loop (`OnlyWhenForced = false`). Before this patch, disabling loop unroll would not run the LoopUnroll pass. After this patch, the LoopUnroll pass is being run, but it restricts unrolling to only the loops marked by a pragma (`OnlyWhenForced = true`). In addition, this patch disables the UnrollAndJam pass when disabling unrolling. Testcase is in clang because it's controlling how the loop optimizer is being set up and there's no other way to trigger the behavior. llvm-svn: 374838
2019-10-15 06:56:07 +08:00
Fix full unrolling with new pass manager. Last we looked at this and couldn't come up with a reason to change it, but with a pragma for full loop unrolling we bypass every other loop unroll and then fail to fully unroll a loop when the pragma is set. Move the OnlyWhenForced out of the check and into the initialization of the full unroll pass in the new pass manager. This doesn't show up with the old pass manager. Add a new option to opt so that we can turn off loop unrolling manually since this is a difference between clang and opt. Tested with check-clang and check-llvm.
2020-05-05 04:48:56 +08:00
void Helper() {
const int *nodes[5];
int num_active = 5;
while (num_active)
#pragma clang loop unroll(full)
for (int i = 0; i < 5; ++i)
if (nodes[i])
--num_active;
}
// Check br i1 to make sure the loop is gone, there will still be a label branch for the infinite loop.
// CHECK-LABEL-NEWPM: Helper
// CHECK-NEWPM: br label
// CHECK-NEWPM-NOT: br i1
// CHECK-NEWPM: br label
// The old pass manager doesn't remove the while loop so check for 5 load i32*.
// CHECK-LABEL-OLDPM: Helper
// CHECK-OLDPM: br label
// CHECK-OLDPM: load i32*
// CHECK-OLDPM: load i32*
// CHECK-OLDPM: load i32*
// CHECK-OLDPM: load i32*
// CHECK-OLDPM: load i32*
// CHECK-OLDPM: ret